1/5. Differential diagnosis of polyuria and polydipsia in a patient with spinal cord injury.We report the case of a 35-yr-old tetraplegic man who experienced increased water intake, constant thirst, and a copious amount of urine excretion after his spinal cord injury and in whom an intermittent catheterization program was unmanageable. Laboratory evaluation revealed low serum and urine osmolality, which were suggestive of psychogenic polydipsia, and hypokalemia, which might lead to polyuria with a compensatory polydipsia. His water intake was reduced with antidepressant therapy and potassium supplementation and normalized on the third month of the treatment. physicians should be aware of the differential diagnosis of polyuria and polydipsia, which interfere with neurogenic bladder management in patients with spinal cord injury.- - - - - - - - - - ranking = 1keywords = thirst (Clic here for more details about this article) |
2/5. Selective osmoreceptor dysfunction presenting as intermittent hypernatremia following surgery for a pituitary chromophobe adenoma.Intermittent hypernatremia following hypothalamic surgery or trauma is usually attributed to the triphasic dysfunction of vasopressin release (diabetes insipidus, inappropriate vasopressin release, and diabetes insipidus). A 39-year-old patient had hypodipsia and intermittent hypernatremia following hypothalamic surgery for a chromophobe adenoma. Mean arterial pressure fell by 25 percent during orthostasis testing and was associated with an increase in vasopressin levels from 1.3 microU/ml to 12 microU/ml. plasma renin activity and aldosterone increased from 1.1 to 16 ng/ml per hour and from 6.7 to 39 ng/dl, respectively, and remained elevated for three and a half hours after tilt testing. Hypertonic saline infusion, on the other hand, increased serum osmolality from 290 to 304 mOsm/kg but did not result in a significant rise in vasopressin levels (all were less than 1 microU/ml). These results are consistent with a selective dysfunction of the osmoreceptor pathways of vasopressin release and intact volume receptor-mediated pathways. patients with intermittent hypernatremia following hypothalamic surgery or trauma should be questioned specifically regarding thirst. If it is impaired or absent, these patients should be watched carefully, not only for the development of triphasic dysfunction of vasopressin release, but also for a selective osmoreceptor dysfunction associated with thirst deficits as found in patients with "essential hypernatremia."- - - - - - - - - - ranking = 2keywords = thirst (Clic here for more details about this article) |
3/5. Lack of thirst, osmoreceptor dysfunction, early puberty and abnormally aggressive behaviour in two boys.Two unrelated boys (C.C. 13 years; J.W. 18 years) presenting with early puberty and episodes of aggressive behaviour were found to have hypernatraemia and hypodipsia. plasma vasopressin (AVP) levels were inappropriately low in relation to plasma osmolality, but the patients did not have diabetes insipidus since 24 h urinary volumes were less than 1 litre and the maximal urinary osmolality was 1232 in C.C. and 950 in J.W. plasma renin activity was elevated (greater than 2000 mg AI/1/h) although aldosterone concentrations were normal. Excretion of a water load (20 ml/kg) was delayed, but plasma renin and aldosterone fell with increased naturesis. An infusion of 0.85 mol/l saline produced a rise in AVP in C.C. but not in J.W. insulin and hypotension resulted in the release of AVP in both boys suggesting a selective defect of osmoreceptor function. Hyperprolactinaemia and an exaggerated PRL response to TRH were also noted but no intracranial lesion was demonstrable on CT scan. These boys appear to have a hypothalamic syndrome with early puberty, hyperprolactinaemia, hypodipsia and osmoreceptor dysfunction which may be associated with aggressive behaviour.- - - - - - - - - - ranking = 4keywords = thirst (Clic here for more details about this article) |
4/5. Hypo-osmolal syndrome due to prolonged nausea.hyponatremia and hypo-osmolality developed in a 70-year-old patient. It was probably mediated by hypersecretion of antidiuretic hormone, which, in turn, was due to prolonged nausea and vomiting. Severe esophagitis was the cause of the nausea. The patient was not given large amounts of fluids intravenously, and it is likely that she continued to drink for nondipsetic reasons. In view of her medical history of neurosyphilis, the possibility of a disturbance in the mechanism of thirst regulation is discussed, but remains unproved.- - - - - - - - - - ranking = 1keywords = thirst (Clic here for more details about this article) |
5/5. Recurrent hypernatremia; a proposed mechanism in a patient with absence of thirst and abnormal excretion of water.A 7-year-old girl twice developed severe hypernatremia (serum sodium values up to 194 mEq/l) without obvious cause. The ability of her kidneys to conserve water was normal, and increasing her plasma osmolality stimulated an appropriate ADH response. Unable to excrete a water load, her kidneys continued to conserve water even with a serum sodium concentration of 133 mEq/l. She was never thirsty and did not ingest sufficient fluid by choice. Although there was no demonstrable anatomic lesion, we postulate a localized defect of her thirst center. This may have modified release of ADH and resulted in an inability to dilute the urine by interrupting a pathway that could exist from the thirst center to the supraoptic nuclei. A therapeutic regimen based on these studies has prevented further hypernatremia.- - - - - - - - - - ranking = 7keywords = thirst (Clic here for more details about this article) |