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As outlined earlier buy astelin 10 ml free shipping allergy treatment shot, the diminished effective volume order 10 ml astelin allergy treatment yorba linda ca, may lead to renal hypop- accurate measurement of blood pressure is an essen- erfusion and subsequent renal scarring buy 10 ml astelin free shipping allergy symptoms chest. Upper urinary tial part of the physical assessment of the child with tract infections 10 ml astelin amex allergy testing norman ok, and especially repeated episodes of suspected or confirmed hypertension. In children with pyelonephritis in the first few years of life, may pre- an unclear etiology to their hypertension, blood pres- dispose to renal parenchymal scars that lead to renin- sure should be measured in all four extremities. Blood pressure in the lower extremi- end-organ damage, such as left ventricular hypertrophy, ties that is not higher than measurements in the upper arteriolar narrowing and hyperreactivity, and structural extremity is suggestive of a coarctation or other nar- and functional measures of endothelial dysfunction rowing of the aorta and is often associated with dimin- such as elevated carotid intimal medial thickness and ished femoral pulses. Previous the physical exam should also include fundoscopic, studies have shown that children presenting with hyper- cardiovascular, pulmonary, and neurologic exams. Somers abdomen should be auscultated for abdominal bruits alocorticoid excess is suspected as plasma renin activ- that, although uncommon, can accompany renovascu- ity is typically suppressed. As these studies are typi- dence of a systemic disease that may explain the elevated cally sent out to reference laboratories, their values are blood pressure. Similarly, several genetic syndromes not helpful in the acute management of hypertension. These include neurofibromatosis (café-au-lait with the initial screening studies, prior to use of potent spots, axillary freckling, Lisch nodules), tuberous scle- vasodilatory antihypertensives. An ultrasound provides infor- stature, shield chest, upturned mouth, webbed neck), mation about differential renal size, hydronephrosis, and Williams syndrome (overfriendly personality, echotexture, and cystic change and, thus, is a good cognitive impairment, prominent ears). As the medical condition stabilizes, scarring needs to be confirmed or is highly suspected. A urinalysis should be performed Doppler study does not, however, rule out renal artery on a freshly voided urine sample and, if the dipstick is stenosis, especially stenosis in smaller segmental positive for blood or protein, should include microscopy arteries not appreciated well by Doppler. For example, tachy- careful ophthalmologic exam may also give information cardia in the absence of pain or agitation suggests as to the chronicity of the child’s hypertensive state. Plasma renin activity and aldosterone levels are In the child with sustained blood pressures exceeding the helpful only if their results are unequivocally low or 99th percentile, diagnostic evaluation and therapy need high. The tempo and urgency Chapter 12 Hypertension in the Pediatric Intensive Care Unit 177 Table 12. The blood pressure Sodium nitroprusside is a powerful arteriolar and should be lowered by 20–30% in the first 2–3 h. For decades, its rapid onset of action the blood pressure is in a range that is not acutely dan- with short half life has made it a first-line option for gerous for the patient, the blood pressure should be continuous antihypertensive infusion. Nitroprusside lowered more gradually to at least the 95th percentile acts as a donor of nitric oxide, which mediates its reference blood pressure over the next several days or potent vasodilatory characteristics. Patients with liver disease or reduced renal The choice of agent should focus on the presumed function should have cyanide levels followed. More underlying mechanism of the hypertension as well as specifically, thiocyanate levels should be monitored local custom and clinician’s familiarity with specific in patients on nitroprusside for more than 72h or in agents. Somers Additionally, nitroprusside may increase intracranial bypass surgery for congenital cardiac disease. Its toxicities are relatively limited but include reflex tachycardia and tachyphy- 12. This agent will likely and Esmolol find greater use given its therapeutic profile, espe- cially in children with hypertension who may also Labetalol may be used both via continuous infusion and benefit from increased renal perfusion. It is the only drug that is both limited clinician familiarity with its use may impact its an alpha- and beta-blocker. It should be used judiciously in children with other agents may be appropriate or effective. Hydralazine is a commonly used vasodilator with Esmolol is a selective beta-blocker used as a con- rapid onset that often can be titrated to achieve good tinuous infusion in children primarily in the setting of blood pressure control. Its toxicities Nifedipine is another short-acting agent and has include bradycardia and congestive heart failure. The use of short-acting nifedipine in children has been found to be very widespread among Nicardipine is a dihydropyridine calcium channel blocker clinicians treating children with hypertension, and of the same class as nifedipine and amlodipine. In spite of suboptimal compared with oral ingestion of an intact earlier concerns of cardiovascular collapse in young capsule. Sublingual administration requires aspiration infants from calcium channel blockers, nicardipine has of liquid from within the gelcap and subsequent dose been used safely in both preterm and term neonates and, estimation; moreover, absorption after sublingual pro- in three studies involving neonates, no adverse events vision is erratic. Moreover, nicardipine was appropriate for those scenarios where renin-mediated found as effective as nitroprusside in adult cohorts. Use of nica- pertensives and is dosed every 8–24h in infants and rdipine also allows transition over to a long-acting oral children [41]. Its use for hypertension in neonates or in calcium channel blocker such as amlodipine or extended children with cystic kidney disease, congenital urologic release nifedipine. It Fenoldopam is in a unique class of dopamine D1 recep- should be used with caution in renovascular disease as tor agonists. The pediatric experience with fenoldopam renal perfusion is renin-dependent in those settings. Loop diuretics (furosemide, bumetanide) are normal blood pressure readings are obtained consist- the most potent diuretics in clinical use, blocking 25% ently. Depending on particular clinical circumstance, of tubular sodium reabsorption at the thick ascending some children may benefit from even lower chronic limb of the loop of Henle. The salt retention that may occur volume overload when oral diuretics cannot be utilized with prolonged use may lead to tachyphylaxis, and or have been ineffective. Additionally, because of the the addition of low-dose diuretic augments the anti- compensatory sodium retention that follows long-term hypertensive effect. Rare patients develop extremity vasodilator and calcium channel blocker use, diuret- edema that may also respond to diuretics. Thiazides may release nifedipine is formulated as a capsule that must serve a similar adjunctive function for loop diuretics, be swallowed intact and may be difficult for younger as increased sodium reabsorption more distal to the children to swallow. Amlodipine has been studied in thick ascending limb can blunt the natiuresis and water specific pediatric trials [12, 28, 34] and is approved loss expected with loop diuretics [29]. Although for- from its intermittent dosing, furosemide or bumeta- mulated to be swallowed as a whole tablet, amlodipine nide can be administered as a continuous infusion for may be crushed and there is extensive clinical use with refractory volume overload. The choice of antihypertensive agent should hyperreninemic hypertension due to renal parenchy- address the presumed underlying pathophysiology of mal scarring. Finally, this class is teratogenic and In the hospitalized hypertensive child, diuretics are postmenarchal girls taking these medications should used primarily in glomerulonephritis where volume be counseled about abstinence or contraception. They may, nonetheless, hypertensive urgency or emergency where acute organ play a role in antihypertensive therapy even in children dysfunction is present, prompt management and evalu- with normal baseline cardiac status, for instance, in ation is essential. As most causes of severe hyper- individuals already on vasodilator therapy but with tension are related to kidney disease, the evaluation tachycardia and suboptimal blood pressure control or in should focus on these etiologies. Early consultation Chapter 12 Hypertension in the Pediatric Intensive Care Unit 181 with a pediatric nephrologist will facilitate the evalu- in neonates with an insufficient response to conventional ation, focus laboratory investigation and imaging, and diuretics. Pediatr Nephrol 21:527–32 of acute hypertension should be simultaneous with its 7. The choice of antihypertensive agent should of the safety of short-acting nifedipine in children with reflect the putative etiology of the hypertension. Pediatr Nephrol 17:35–40 addition to mainstays of antihypertensive therapy in the 8. Therapy should J Pediatr 139:38–43 utilize the fewest medications with sequential maxi- 12.
Bruises may be associated with other visible evidence of injury purchase 10 ml astelin overnight delivery zopiclone allergy symptoms, such as abrasions and lacerations discount 10 ml astelin amex allergy treatment pipeline, and these lesions may obscure the underlying bruise buy astelin 10 ml visa allergy medicine herbal. Bruising may need to be differentiated from purpura astelin 10 ml without prescription allergy shots yeast infections, which develop spon- taneously in those with a hemorrhagic tendency and in the elderly and tend to be rather blotchy, are less regular in outline, and are usually confined to the forearms and lower legs. Bruises vary in severity according to the site and nature of the tissue struck, even when the force of the impact is the same. Where there is an underlying bony surface and the tissues are lax, as in the facial area, a relatively light blow may produce considerable puffy bruising. Bruises can enlarge over a variable period of time, which can be mis- leading regarding the actual site of injury. Because a bruise is a simple mechan- ical permeation of the tissues by blood, its extension may be affected by movement and gravity. Further difficulties arise if a bruise, as it extends, tracks along tissue planes from an invisible to a visible location. Bruising of this kind may not become apparent externally for some time and then some distance from the site of the original impact. This delay in the appearance of bruising is of con- siderable significance because absence of apparent injury at an initial examina- tion is not necessarily inconsistent with bruising becoming apparent 24–48 hours later. Thus, in cases of serious assault, it is often advisable to conduct a further examination a day or so later. Generally, bruises, unless superficial and intradermal, tend to be nonspe- cific injuries, and it is usually not possible to offer any detailed opinions on the agent responsible. However, some bruises may have a pattern (a patterned bruise), or because of their shape or size or location, may have particular sig- nificance. Common patterning types include petechial bruising reproducing the texture of clothing, the ridge pattern from the sole of a shoe or tire, or the streaky linear purple bruising seen on the neck, wrists, or ankles caused by the application of a ligature. Beating with a rod-like implement often leaves a patterned bruise consisting of an area of central pallor outlined by two narrow parallel bands of bruising, so-called tramline bruising (see Fig. Other bruises of particular medicolegal significance are the small circu- lar or oval bruises, usually approx 1–2 cm in diameter, characteristic of fin- gertip pressure from either gripping or grasping with the hand, prodding with the fingers, or the firm impact of a knuckle. They may be seen on the limbs in cases of child abuse when the child is forcibly gripped by the arms or legs and shaken or on the abdomen when the victim is poked, prodded, or punched. However, such nonaccidental injuries must be differentiated from bruises seen on toddlers and children associated with normal activities, play, or sports. Bruises may be seen on the neck in cases of manual strangulation and are then usually associated with other signs of asphyxia. When sexual assault is alleged, the presence of bruising on the victim may help support the victim’s account and give an indication of the degree of violence that was used. For example, grip marks or “defense” injuries may be present on the upper arms and forearms, whereas bruising on the thighs and the inner sides of the knees may occur as the victim’s legs are forcibly pulled apart. Bruising of the mouth and lips can be caused when an assailant places a hand over the face to keep the victim quiet. Love bites (“hickeys”) may be present often in the form of discrete areas of ovoid pete- chial bruising on the neck and breasts. However, it is important to recognize that the latter may be the sequelae of consensual sexual encounters. Abrasions An abrasion (or a graze) is a superficial injury involving only the outer layers of the skin and not penetrating the full thickness of the epidermis. Abra- sions exude serum, which progressively hardens to form a scab, but they may also bleed because occasionally they are deep enough to breach the vascular papillae that corrugate the undersurface of the epidermis in which case frank bleeding may be present at an early stage. More superficial abrasions that barely damage the skin with little or no exudation of serum (and thus little or no scab formation) may be termed brush or scuff abrasions. Scratches are lin- ear abrasions typically caused by fingernails across the surface of the skin. Pointed but noncutting objects may also cause linear abrasions and to differ- entiate them from fingernail scratches may be termed “point abrasions. Thus they may have a linear appearance, and close examination may show ruffling of the superficial epidermis to one end, indicating the direction of travel of the opposing surface. Thus, a tangential blow could be horizontal or vertical, or it may be possible to infer that the victim had been dragged over a rough surface. The patterning of abrasions is clearer than that of bruises because abra- sions frequently take a fairly detailed impression of the shape of the object causing them and, once inflicted, do not extend or gravitate; therefore, they indicate precisely the area of application of force. In manual strangulation, small, crescent-shaped abrasions caused by the fingernails of the victim or assailant may be the only signs visible on the neck. A victim resisting a sexual or other attack may claw at her assailant and leave linear parallel abrasions on the assailant’s face. Some abrasions may be contaminated with foreign mate- rial, such as dirt or glass, which may have important medicolegal significance. In such cases, consultation with a forensic scientist can ensure the best means of evidence collection and preservation. Lacerations Lacerations are caused by blunt force splitting the full thickness of the skin (see Fig. Boxers classically develop lac- erations when a boxing glove presses on the orbital rim. When inflicted deliberately, the force may cause the assailant and weapon to be contaminated with blood. Lacerations have characteristic features but often mimic incised wounds (or vice-versa), particularly where the skin is closely applied to underlying bone, for example, the scalp. Close examination of the margins of the wound, which are usually slightly inverted, normally resolves the issue. Blood vessels, nerves, and delicate tissue bridges may be exposed in the depth of the wound, which may be soiled by grit, paint fragments, or glass. The shape of the laceration may give some indication regarding to the agent responsible. For example, blows to the scalp with the circular head of a hammer or the spherical knob of a poker tend to cause crescent-shaped lacera- tions. A weapon with a square or rectangular face, such as the butt of an axe, may cause a laceration with a Y-shaped split at its corners. Incisions These wounds are caused by sharp cutting implements, usually bladed weapons, such as knives and razors, but sharp slivers of glass, the sharp edges of tin cans, and sharp tools, such as chisels, may also cause clean-cut incised injuries. Axes, choppers, and other similar instruments, although capable of cutting, usually cause lacerations because the injury caused by the size of the instrument (e. Mixed wounds are common, with some incised element, some laceration, bruising, and swelling and abrasion also present. Machetes and other large-blade implements are being used, pro- ducing large deep cuts known as slash or chop injuries. They Injury Assessment 141 gape, and the deeper tissues are all cut cleanly in the same plane. If the blade of the weapon is drawn across the skin while it is lax, it may cause a notched wound if the skin creases.
In mammals Appropriate dosages for glucocorticoids in birds have the antibody-forming cells (“bone marrow-derived” or not been fully established and are currently being “bursa-equivalent” [B-] lymphocytes and plasma investigated astelin 10 ml fast delivery peanut allergy symptoms how quickly. Dosage guidelines are based on data in cells) are relatively resistant to the suppressive ef- mammals discount 10 ml astelin free shipping allergy testing unreliable. Equivalent Dose (mg) Pharmacologic concentrations of corticosterone in Based on Mineralocorticoid birds can cause involution of the cloacal bursa buy generic astelin 10 ml line new allergy treatment 2014, thy- Glucocorticoid Anti-inflammatory Potency mus and spleen astelin 10 ml amex allergy forecast oakville, resulting in suppression of both Potency humoral and cell-mediated immunity. Cortisone and cortisol (hydrocortisone) have the highest mineralocorticoid activity and are the corticosteroids of choice for re- placement therapy after adrenalectomy or in (iatro- genic) hypoadrenocorticism. Supplemental admini- stration of the mineralocorticoid, fludrocortisone, is suggested in these cases. Endoscopy of the trachea revealed a proliferative costeroids and are suffering from iatrogenic secon- mass occluding the majority of the lumen. At necropsy, an aspergilloma was detected in the mid-cer- vical area of the trachea. Low levels late at night nosuppressive and chemotherapeutic doses are 2-4 release the pituitary from feedback inhibition and mg/kg prednisolone daily. When the same total chemotherapy for lymphoreticular neoplasia because amount of glucocorticosteroids is given in divided of their antimitotic effects on lymphoid tissue. Therefore, prednisone and cor- however, some controversy about the exact timing of tisone are not effective when applied topically. The situation teroid therapy is indicated, appropriate considera- might be reversed in nocturnal birds. Local corticosteroid therapy should be consid- men should be tapered down to the least toxic dose. However, the clinician should be aware therapy has to be given for periods over two weeks, that high or even toxic blood levels of steroids can alternate-day therapy should be considered. The use of nonsteroidal anti-inflammatory agents are used to simulate the normal physiologic drugs can be used on the “off” days during the taper- corticosterone cycle. These lesions represent a period of malnutrition or stress while the feathers were developing. They Iatrogenic Hyperadrenocorticism-like Disease can also be induced by a single injection of a glucocor- Exogenous glucocorticoids cause hyperphagia while ticoid. Administration of glucocorticoids strongly reducing growth and body weight in birds. There is a suppresses growth and increases protein catabo- marked increase in fat deposition (lipogenesis) and a lism,24 and these lesions probably reflect a short concomitant increase in protein catabolism. Choles- period of decreased amino acid available to the devel- terol levels increase, and true lipemic conditions may oping feather. Chronic malnutrition and chronic develop as a result of glucocorticoid injections. Fur- stress in birds with developing feathers will result in thermore, gluconeogenesis is increased (production more severely affected feathers. Calcium absorption from the intestinal tract A benign or malignant tumor of chromaffin tissue is reduced after administration of betamethasone may cause hypersecretion of epinephrine or no- and cortisol. Corticosterone increases the glomerular repinephrine, which in man is known to lead to hy- filtration rate which, together with glucosuria, may pertension and associated symptoms such as profuse be recognized as polyuria and polydipsia. A pheochromocy- toma of the adrenal gland in a 14-week-old broiler Iatrogenic Secondary Hypoadrenocorticism 15 pullet has been reported. Glucocorticoids exert a negative feedback influence The only obvious abnormality was an enlarged left at the hypothalamo-hypophyseal level and suppress adrenal gland measuring 15 mm in diameter. Fail- ure of the adrenal gland to respond to stress factors may result in adrenocortical insufficiency. Many stressors are known to induce corticosterone secre- tion in birds: extreme environmental temperatures, Endocrine Control handling, immobilization, anesthesia, infection, frus- tration, fear, housing, noise, food and water depriva- of Feather Formation tion and hypovitaminosis A. Adrenocortical failure and shock may occur in birds exposed to one or more stressful situation following iatrogenic glucocorticoid administration. Exposure to high doses over a pro- turbances in feather formation of unknown etiology. Replacement therapy is indicated in length, which controls the neurohumoral factors. Neural control of feather formation has been demon- strated by growth retardation of feathers when de- Stress Marks nervation occurs. The metabolic processes that un- A common disorder of developing feathers is the sym- derlie feather formation are regulated by the thyroid metrical development of stress marks or hunger and the gonads. The presence of thyroid hormone, however, is essential for the growth, differ- In some birds (eg, Galliformes, Passeriformes, An- entiation of structure and formation of feather pat- seriformes), feather color and pattern vary with the tern. The importance of thyroid hormone for feather age, gender and season, and these characteristics are formation is generally similar in young and mature governed by hormonal influences of the gonads. In some birds, this thyroid dependence affects these birds, the adult plumage, unlike the juvenile the rate of feather growth and formation of vane plumage, develops under the influence of at least two structure and in others, it affects the pigmentation endocrine glands. In these birds the plumage does not change under influence of In thyroidectomized birds, the lower parts of the plasma concentrations of sex hormones but is gov- feather are underdeveloped, while in hyperthyroid- erned by the autosome: sex chromosome ratio and ism, these parts develop most vigorously. The roidism, the vanes of the feathers are narrower and influence of sex hormone in the former group in each there is a partial reduction of the barbs. In a number feather-forming process is realized only at a defini- of fowl breeds, hypothyroidism is accompanied by tive level of metabolism that is maintained by thy- partial or complete replacement of black eumelanin roid hormone (female plumage does not develop in by brown pheomelanin, while in hyperthyroidism thyroidectomized birds given estrogen). The black pig- bird is adequately saturated with thyroid and sex ment can be formed in the bird’s body at only a hormones, the feathers that develop should be certain concentration of thyroid hormone. Under conditions of hypothyroidism or athyreosis, the feathers that de- Molting is possible only as the result of complex velop are uniform in structure and should be termed hormonal influences. Molting occurs during a period the athyreoid type of plumage (and consequently also of depressed sexual activity. The male plumage is potentially an attribute of both genders, and the female hormones play the principal When the duration of light is decreased, or a long role in gender differences in the plumage of Gallifor- period of artificial daylight is suddenly replaced by a mes and Anseriformes. When a rooster, drake or cock short one, sexual activity declines or ceases and molt- pheasant is castrated, no changes are produced in the ing begins. When a ods of daily light associated with declining sexual castrated rooster or a neutered hen undergoes an activity are needed for the proliferation of feather ovarian transplant, female-type plumage develops. Sudden transi- tion to darkness after prolonged exposure to length- ened periods of daily light produces vigorous molting in various birds. It should be remembered that many avian species Diabetes Mellitus must be exposed to natural photoperiods to allow a normal hypothalamic-pituitary control of the molt- ing process. Improper photoperiods may be an impor- Spontaneous diabetes mellitus has been reported in tant cause of feathering disorders in companion birds a variety of granivorous avian species, including the kept indoors. One case of spontaneous diabetes ment requires that appropriate nutrients for feather 103 mellitus has been reported in a raptor. A tentative diagno- body’s increased requirements of thyroid hormone in sis can be made by demonstrating glucosuria while a connection with the development of new feathers. Glucocorticoids, epinephrine, There are some striking differences between birds glucagon and growth hormone can all induce hyper- and mammals with respect to pancreatic control of glycemia and impaired glucose tolerance. The insulin content of the duction of these hormones may occur with tumors of pancreas of granivorous birds is about one-sixth that the hormone-producing cells or paraneoplastic syn- of mammalian pancreata, while the glucagon content dromes (“ectopic” hormone production). Circulating plasma concentrations of glucagon are 10 to 50 times higher In man, hyperglucagonemia may be associated with in birds than in mammals.
Considerable evidence suggests that gluten sensitivity may be a contributing factor in some patients 10 ml astelin with visa allergy with cough. Diet The diet should be free of known allergens and astelin 10 ml generic allergy testing eczema, if gluten sensitivity is present purchase astelin 10 ml on line allergy zone map, all gluten sources buy astelin 10 ml line allergy zone map. Otherwise, the guidelines in the chapter “A Health-Promoting Diet” are appropriate. Compression of this nerve causes weakness; pain in gripping; and burning, tingling, or aching that may radiate to the forearm and shoulder. It occurs most often in pregnant women, women taking oral contraceptives, menopausal women, or patients on hemodialysis due to kidney failure. Causes Any factor that causes the carpal tunnel to get smaller or its contents to swell can lead to carpal tunnel syndrome. To prevent permanent nerve damage, however, surgery should not be delayed beyond three years after first onset of symptoms. Open carpal tunnel release surgery is one of the most commonly performed outpatient surgeries and is less expensive than the newer endoscopic procedures. A detailed review reported no difference in long-term results between the procedures, but pain is reduced the first two weeks following the endoscopic surgery compared with open procedures. Specialized splints have not been proven more effective than a good-quality, well-fitted over-the-counter splint. Alternating hot and cold water treatment (contrast hydrotherapy) provides a simple, efficient way to increase circulation to the area and reduce swelling. Immersion of the hand past the wrist in hot water for three minutes, followed by immersion in cold water for 30 seconds, repeated three to five times, will increase local circulation, thereby increasing local inflow of nutrients, increasing elimination of waste products, and decreasing pain. If B6 does not produce results within a few weeks, P5P should be tried at 10 mg per day. Celadrin Celadrin is a proprietary mixture of cetylated fatty acids that has been shown to affect several key factors that contribute to inflammation. Studies have assessed both the oral and the topical use of Celadrin in the treatment of osteoarthritis (see the chapter “Osteoarthritis”). Acupuncture A randomized controlled study comparing an oral steroid (prednisolone 20 mg for two weeks, then 10 mg for two weeks) vs. Diet Follow the general recommendations given in the chapter “A Health-Promoting Diet. Cataracts • Clouding or opacity in the crystalline lens of the eye • Gradual loss of vision Cataracts are white, opaque blemishes on the normally transparent lens of the eye. They occur as a result of damage to the protein structure of the lens, similar to the damage that occurs to the protein of eggs when they are boiled or fried. Cataracts are the leading cause of impaired vision and blindness in the United States. Approximately 6 million Americans have some degree of vision- impairing cataract, and among Medicare recipients, cataract surgery is the most common major surgical procedure, with nearly 1 million procedures each year. Cataracts can be classified by location and appearance of the lens opacities, by cause or significant contributing factor, and by age of onset. Many factors may cause or contribute to the progression of lens opacity, including ocular disease, injury, or surgery; systemic diseases (e. Aging-related cataracts (senile cataracts) are discussed in this chapter, and diabetic and galactose-induced cataracts (sugar cataracts) are discussed in the chapter “Diabetes. The majority of the geriatric population displays some degree of cataract formation. Even with normal aging there is a progressive increase in size, weight, and density of the lens. Causes In cataract formation, the normal protective mechanisms are unable to prevent free radical damage to the cells of the lens. Lutein Lutein, a yellow-orange carotene that offers significant protection against macular degeneration, also helps protect against cataract formation. In 1992 a study showed that consumption of spinach (high in lutein) was inversely related to the risk of cataracts severe enough to require extraction. Vitamin C A high dietary intake of vitamin C from either dietary sources or supplements has been shown to protect against cataract formation. Several clinical studies have demonstrated that vitamin C supplementation can halt cataract progression and, in some cases, significantly improve vision. For example, in one study conducted in 1939, 450 patients with cataracts were started on a nutritional program that included 1 g per day of vitamin C, which resulted in a significant reduction in cataract development. It appears that the dosage of vitamin C necessary to increase the vitamin C content of the lens is 1,000 mg. In order for these concentrations to be maintained in these tissues, the body has to generate enormous amounts of energy to pull vitamin C out of blood against this tremendous gradient. Keeping blood vitamin C concentrations elevated helps the body concentrate vitamin C into active tissue by reducing the gradient. That is probably why such high dosages are required to raise the vitamin C content of the lens. In another study, 450 patients with incipient cataracts were started on a nutritional program that included 1,000 mg per day of vitamin C, which led to a significant reduction in cataract development. This study may have failed to show benefit because it was below the threshold of 1,000 mg per day of vitamin C. Selenium and Vitamin E Selenium and vitamin E are antioxidants known to function synergistically. Maintaining proper selenium levels appears to be especially important because the lens antioxidant enzyme glutathione peroxidase requires selenium. Low selenium levels greatly promotes cataract formation; early studies have shown that selenium content in the human lens with a cataract is only 15% of normal levels. Selenium levels in the serum and aqueous humor were found to be significantly lower in the patients with cataracts (serum, 0. However, selenium levels in the lens itself did not significantly differ between the patients with cataracts and the controls. The most important finding of the study was the decreased level of selenium in the aqueous humor in patients with cataracts. Excessive hydrogen peroxide levels, up to 25 times normal, are found in the aqueous humor in patients with cataracts and are a key underlying factor in cataract formation. Because selenium-dependent glutathione peroxidase is responsible for the breakdown of hydrogen peroxide, it is quite obvious why low selenium levels appear to be a major factor in the development of cataracts. As previously described, vitamin E supplementation alone does not slow the progression of cataract formation. Levels of these necessary cofactors are greatly reduced in lenses with cataracts; copper and zinc levels are reduced by more than 90%, and manganese by 50%. Studies of human senile cataracts have demonstrated decreased levels of tetrahydrobiopterin and pteridine-synthesizing enzymes. However, no more than 10 mg per day of riboflavin should be taken by people with cataracts, because it is a photosensitizing substance—that is, riboflavin reacts with the light to form superoxide free radicals.
