Nephrotic syndrome hyponatremia

Hypotonic hyponatremia with an increase in ECF is also known as dilutional hyponatremia. In this scenario, patients have an excess of total body sodium and TBW however, the excess in TBW is greater than the excess in total body sodium. Common causes include CHF, hepatic cirrhosis, and nephrotic syndrome. Treatment includes sodium and fluid restriction in conjunction with treatment of the underlying disorder—for example, salt and water restrictions are used in the setting of CHF along with loop diuretics, angiotensin-converting enzyme inhibitors, and spironolactone.15... 

Renal effects Acute renal insufficiency, interstitial nephritis with hematuria, nephrotic syndrome, proteinuria, hyperkalemia, hyponatremia, renal papillary necrosis, and other renal medullary changes may occur. 

The most common cause of hyponatremia in hospital patients is SIADH. However, other disorders can cause dilutional hyponatremia and must be differentiated from SIADH. These conditions include (1) congestive heart failure, (2) renal insufficiency, (3) nephrotic syndrome, (4) liver cirrhosis, and (5) hypothyroidism. Excessive administration of hypotonic fluids and treatment with drugs that stimulate AVP (e.g., chlorpropamide, vincristine, clofibrate, carbamazepine, nicotine, phenothiazines, and cyclophosphamide) can cause dilutional hyponatremia as well. Hyponatremia may also occur from renal or extrarenal sodium losses (depietional hyponatremia) as a result of vomiting, diarrhea, excessive sweating, diuretic abuse, saltlosing nephropathy, or mineralocorticoid deficiency. 

Hyponatremia associated with an increase in ECF volume occurs in conditions in which renal sodium and water excretion are impaired. Patients with cirrhosis, congestive heart failure, and nephrotic syndrome have an expanded ECF volume and edema, but a decreased EABV. The decreased EABV results in renal sodium retention, and eventually ECF volume expansion and edema. At the same time, there is nonosmotic release of ADH and retention of water in excess of sodium, thus perpetuating the hyponatremia. 

Other potentially treatable causes of asymptomatic hyponatremia associated with an expanded ECE volume include nephrotic syndrome and cirrhosis. ACEls may be used to decrease proteinuria... 

Diuretics are used widely for the treatment of hypertension see Chapter 32), and loop diuretics appear to lower blood pressure as effectively as Na+-CL symporter inhibitors e.g., thiazides and thiazide-hke diuretics) while causing smaller perturbations in the Upid profile. However, the short elimination half-lives of loop diuretics render them less useful for hypertension than thiazide-type diuretics. The edema of nephrotic syndrome often is refractory to other classes of diuretics, and loop diuretics often are the only drugs capable of reducing the massive edema associated with this disease. Loop diuretics also are employed in the treatment of edema and ascites of hepatic cirrhosis however, care must be taken not to induce encephalopathy or hepatorenal syndrome. In patients with a drug overdose, loop diuretics can be used to induce a forced diuresis to facilitate more rapid renal elimination of the offending drug. Loop diuretics, combined with isotonic saline administration to prevent volume depletion, are used to treat hypercalcemia. Loop diuretics interfere with the kidney s capacity to produce a concentrated urine. Consequently, loop diuretics combined with hypertonic saline are useful for the treatment of hfe-threatening hyponatremia. Loop diuretics also are used to treat edema associated with chronic renal insufficiency. Most patients with ARE receive... 

OTHER WATER-RETAINING STATES In patients with congestive heart failure, cirrhosis, or nephrotic syndrome, ejfective blood volume often is reduced, and hypovolemia frequently is exacerbated by the liberal use of diuretics. Since hypovolemia stimulates vasopressin release, patients may become hyponatremic owing to vasopressin-mediated retention of water. The development of potent orally active receptor antagonists and specific inhibitors of water chaimels in the collecting duct would provide an effective therapeutic strategy not only in patients with SIADH but also in the much more common setting of hyponatremia in patients with heart faftme, cirrhosis, or nephrotic syndrome. 

Electrolyte balance Hyponatremia in a 74-year-old man with nephrotic syndrome due to a salt-losing nephropathy was attributed to voriconazole. The serum antidiuretic hormone (ADH) concentration and plasma renin activity were raised, and there was a high urine sodium concentration, despite volume depletion and a low serum osmolality [33" ]. 

Hypervolemic hypotonic hyponatremia— increase in water without an equal increase in sodium. Occurs with cirrhosis, hypoproteinemia (low albumin), heart failure, and nephrotic syndrome. 

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