Chapter 036. Edema (Part 5) Idiopathic Edema This syndrome, which occurs almost exclusively in women, is characterized by periodic episodes of edema (unrelated to the menstrual cycle), frequently accompanied by abdominal distention. Diurnal alterations in weight occur with orthostatic retention of NaCl and H 2 O, so that the patient may weigh several pounds more after having been in the upright posture for several hours. Such large diurnal weight changes suggest an increase in capillary permeability that appears to fluctuate in severity and to be aggravated by hot weather. There is some evidence that a reduction in plasma volume occurs in this condition with secondary activation of the RAA system and impaired suppression of AVP release. Idiopathic edema should be distinguished from cyclical or premenstrual edema, in which the NaCl and H 2 O retention may be secondary to excessive estrogen stimulation. There are also some cases in which the edema appears to be diuretic-induced. It has been postulated that in these patients chronic diuretic administration leads to mild blood volume depletion, which causes chronic hyperreninemia and juxtaglomerular hyperplasia. Salt-retaining mechanisms appear to overcompensate for the direct effects of the diuretics. Acute withdrawal of diuretics can then leave the Na + -retaining forces unopposed, leading to fluid retention and edema. Decreased dopaminergic activity and reduced urinary kallikrein and kinin excretion have been reported in this condition and may also be of pathogenetic importance. Idiopathic Edema: Treatment The treatment of idiopathic cyclic edema includes a reduction in NaCl intake, rest in the supine position for several hours each day, and the wearing of elastic stockings (which should be put on before arising in the morning). A variety of pharmacologic agents, including angiotensin-converting enzyme inhibitors, progesterone, the dopamine receptor agonist bromocriptine, and the sympathomimetic amine dextroamphetamine, have all been reported to be useful when administered to patients who do not respond to simpler measures. Diuretics may be helpful initially but may lose their effectiveness with continuous administration; accordingly, they should be employed sparingly, if at all. Discontinuation of diuretics paradoxically leads to diuresis in diuretic-induced edema, described above. Localized Edema (See also Chap. 243) Edema originating from inflammation or hypersensitivity is usually readily identified. Localized edema due to venous or lymphatic obstruction may be caused by thrombophlebitis, chronic lymphangitis, resection of regional lymph nodes, filariasis, etc. Lymphedema is particularly intractable because restriction of lymphatic flow results in increased protein concentration in the interstitial fluid, a circumstance that aggravates retention of fluid. Generalized Edema The differences among the three major causes of generalized edema are shown in Table 36-2. Table 36-2 Principal Causes of Generalized Edema: History, Physical Examination, and Laboratory Findings Organ System History Physical Examination Laboratory Findings Cardiac Dyspnea with exertion prominent—often associated with orthopnea—or paroxysmal nocturnal dyspnea Elevated jugular venous pressure, ventricular (S 3 ) gallop; occasionally with displaced or d yskinetic apical pulse; peripheral cyanosis, cool extremities, small pulse pressure when severe Elevated urea nitrogen-to-creatinine ratio common; elevated uric acid; serum sodium often diminished; liver enzymes occasionally elevated with hepatic congestion Hepatic Dyspnea infrequent, except if associated with significant degree of ascites; most often a history of ethanol Frequently associated with ascites; jugular venous pressure normal or low; blood pressure lower than in renal or If severe, reductions in serum albumin, cholestero l, other hepatic proteins (transferrin, fibrinogen); liver enzymes elevated, abuse cardiac disease ; one or more additional signs of chronic liver disease (jaundice, palmar erythema, Dupuytren's contracture, spider angiomata, male gynecomastia; asterixis and other signs of encephalopathy) may be present depending on the cause and acuity of liver injury; tendency toward hypokalemia, respiratory alkalosis; macrocytosis from folate deficiency Renal Usually chronic: may be associate d with uremic signs and symptoms, including decreased appetite, altered Blood pressure may be elevated; hypertensive or diabetic retinopathy in selected cases; nitrogenous fetor; periorbital edema may Albuminuria, hypoalbuminemia; sometimes, elevation of serum crea tinine and urea nitrogen; hyperkalemia, metabolic acidosis, (metallic or fishy) taste, altered sleep pattern, difficulty concentrating, restless legs or myoclonus; dyspnea can be present, but generally less prominent than in heart failure predominate; pericardial friction rub in advanced cases with uremia hyperphosphatemia, hypocalcemia, anemia (usually normocytic) Source: From Chertow. The great majority of patients with generalized edema suffer from advanced cardiac, renal, hepatic, or nutritional disorders. Consequently, the differential diagnosis of generalized edema should be directed toward identifying or excluding these several conditions. . Chapter 036. Edema (Part 5) Idiopathic Edema This syndrome, which occurs almost exclusively in women, is characterized by periodic episodes of edema (unrelated to the. diuretic-induced edema, described above. Localized Edema (See also Chap. 243) Edema originating from inflammation or hypersensitivity is usually readily identified. Localized edema due to venous. of fluid. Generalized Edema The differences among the three major causes of generalized edema are shown in Table 36-2. Table 36-2 Principal Causes of Generalized Edema: History, Physical