Idiopathic, sustained, inappropriate secretion of ADH with associated hypertension and thirst

Inappropriate secretion of antidiuretic hormone, polydipsia and hypothalamic calcifications

We studied a 41 year old patient who had pathologic fluid intake of 10 1/day together with syndrome of inappropriate antidiuretic hormone. Imaging studies revealed a lesion of the anterior wall of the third cerebral ventricle. A review of relevant literature indicated several different disturbances by which alterations of thirst, vasopressin-secretion and abnormalities of anterior third ventricle may be associated. The present case presents an unusual and potentially dangerous combination in this spectrum of changes.

Severe symptomatic hyponatremia in elderly outpatients: the role of thiazide therapy and stress

Severe symptomatic hyponatremia (serum sodium level 112 +/- 5.5 mEq/l) was encountered in six elderly outpatients within four days of the onset of thiazide therapy. Associated polydipsia was present in two of these patients, but the thiazides alone appeared responsible in the others. In three other elderly outpatients, severe hyponatremia (serum sodium level 112 +/- 5.25 mEq/l) developed after the acute emotional stress of relocation from their place of abode to a nursing home or hospital. Recurrent episodes of hyponatremia occurred in two patients following reinstitution of diuretic therapy, and, in two other patients, was precipitated by thiazides and stress on different occasions. Severe neurologic manifestations occurred in all patients and were mostly attributed to atherosclerotic dementia or stroke. Two patients died with severe hyponatremia, although all patients in whom cessation of thiazide therapy and water restriction were instituted promptly recovered without permanent sequelae.

Is vasopressin an important hypertensive hormone?

To generate quantitative data relating to the potential hypertensive activity of arginine vasopressin (AVP), 140 and 560 microunits AVP/kg/min were infused chronically in both normotensive dogs and dogs made hypertensive by chronic infusion of either angiotensin II (AII) or aldosterone. The lower rate of AVP infusion increased plasma AVP concentration from 0.4 +/- 0.1 microunits/ml. Mean arterial pressure (MAP) was recorded 24 hours per day, and all dogs were infused continuously with 800 ml of isotonic saline per day. During the initial days of AVP infusion in normotensive dogs, natriuresis, kaliuresis, and water retention were prominent and MAP increased progressively to a peak on Day 6 (30 mm Hg above control). Subsequently, diuresis ensued, net water retention decreased, and MAP fell progressively to only 13 mm Hg above control by Day 12 of AVP infusion. In contrast, in AII or aldosterone hypertensive dogs during AVP infusion, the natriuresis was greatly attenuated, water balance was unchanged or even negative, and MAP either did not increase or increased only transiently. When AVP infusion was terminated in dogs given only AVP, diuresis occurred, and MAP fell gradually over a period of hours to hypertensive levels. In marked contrast, cessation of AVP infusion in dogs with either AII or aldosterone hypertension was associated with a precipitous fall in MAP of 35 to 40 mm Hg within 1 hour: however, this reduction was only transient - over the subsequent hours, both salt and water retention occurred, and MAP returned to previous hypertensive levels. Thus, in the hypertensive models studied, high plasma levels of AVP had relatively weak hypertensive effects. Although variations in plasma AVP concentration were associated with rather pronounced acute effects on MAP, the long-term changes in MAP produced by AVP were either minimal or, in the case of the animals made hypertensive by other agents, nonexistent.