Combination of carbamazepine and chlorpropamide in the treatment of "hyporesponder" pituitary diabetes insipidus

Idiopathic partial central diabetes insipidus

Diabetes insipidus is a rare disorder characterized by the inability to concentrate urine, which results in hypotonic urine and increased urinary volume. It may occur because of antidiuretic hormone deficiency or resistance to its action in the renal tubules. When there is a deficiency in the synthesis of antidiuretic hormones, diabetes insipidus is called central; when there is resistance to its action in the renal tubules, it is said to be nephrogenic. We report a case of idiopathic partial central diabetes insipidus and highlight the management and treatment of the disease.

Management of central diabetes insipidus

The treatment of central diabetes insipidus has not changed significantly in recent decades, and dDAVP and replacement of free water deficit remain the cornerstones of treatment. Oral dDAVP has replaced nasal dDAVP as a more reliable mode of treatment for chronic central diabetes insipidus. Hyponatraemia is a common side effect, occurring in one in four patients, and should be avoided by allowing a regular break from dDAVP to allow a resultant aquaresis. Hypernatraemia is less common, and typically occurs during hospitalization, when access to water is restricted, and in cases of adipsic DI. Management of adipsic DI can be challenging, and requires initial inpatient assessment to establish dose of dDAVP, daily fluid prescription, and eunatraemic weight which can guide day-to-day fluid targets in the long-term.

Carrier detection in the testicular feminisation syndrome: deficient 5 alpha-dihydrotestosterone binding in cultured skin fibroblasts from the mothers of patients with complete androgen insensitivity

Specific binding of 5 alpha-dihydrotestosterone (androgen receptor activity) could not be detected in cultured genital skin fibroblasts (GSF) from two patients with complete androgen insensitivity (CAI). In GSF from the mother of one patient, androgen receptor activity (8.5 fmol/mg cell protein) was reduced in comparison with controls (34.0 +/- 10.1 (SD) fmol/mg protein n = 15). These results favour X linked inheritance of CAI and X inactivation at the androgen receptor locus. Androgen receptors were not detected in GSF of the second mother. It appears that female carriers of CAI could be detected by decreased 5 alpha-dihydrotestosterone binding in GSF. Androgen receptor activity was also undetectable in non-genital skin fibroblasts (NGSF) from the second mother and two further CAI patients. However, in 1 in 10 control NGSF lines androgen receptor activity was at the lower limit of assay sensitivity (1 to 2 fmol/mg protein) demonstrating that NGSF may not be reliable for family studies of androgen receptor deficiency.

Drug management of antidiuretic hormone imbalance following pituitary surgery

ADH imbalance may occur in patients after pituitary surgery. Two cases are presented that demonstrate the problems associated with the disturbance of water metabolism. The medical management of these patients is discussed, with emphasis on the importance of the correct choice of pharmacological agents to control the manifestations of ADH imbalance.

Mannitol osmolar clearance in diabetes insipidus of children

A modified technique of amnnitol-induced diuresis is described, in order to assess renal concentrating ability in infants and children. The infusion of 10% mannitol in 0.9% saline avoided the hypertonic saline overload and the fluid restriction period, both badly tolerated by infants and small children. In a control group of children aged from two months to seven years, the values of T(H2O) plotted against C(OSM) allowed to calculate the adjustment curve y=0.80x0.75, r=0.98 (p is less than 0.0001). In six patients with pituitary diabetes insipidus (PDI), the test was used in order to quantify the degree of ADH deficiency and evaluate the carbamazepine and clofibrate effect, in the renal concentrating mechanism. The test was tolerated perfectly in every case, obtaining qualitative and quantitative data and avoiding the hyponatremia and hypokalemia produced by the mannitol.

Comparison of clofibrate and chlorpropamide in vasopressin-responsive diabetes insipidus

Six patients with vasopressin-responsive diabetes insipidus (DI) received clofibrate and chlorpropamide, singly and in combination. Decrease in urinary output averaged (mean +/- SEM): (1) clofibrate 2 g/day, 47% +/- 6%; (2) chlorpropamide 250 mg/day 59% +/- 5%; (3) clofibrate 2 g/day plus chlorpropamide 125 mg/day, 54% +/- 7%; (4) clofibrate 2 g/day plus chlorpropamide 250 mg/day 61% +/- 4%. Water deprivation tests before and during treatment showed significantly higher basal, final, and peak urinary osmolalities (Uosm) and lower free water clearance (CH20) on chlorpropamide, singly and in combination: clofibrate raised Uosm less but significantly decreased CH2O. Water load tests before and during treatment showed that chlorpropamide, singly and in combination, markedly decreased maximal urinary flow, maximal CH2O, percentage water load excreted, and increased minimal Uosm; clofibrate significantly decreased maximal urinary flow and CH2O only. One patient responded only to combination therapy. Chlorporpamide caused serious hypoglycemia in three of six patients. Clofibrate had no significant side effects.

Pathophysiologic and pharmacologic alterations in the release and action of ADH

The physiologic factors involved in vaseopressin (ADH) release and action are reviewed with emphasis on the interaction between osmotic and volume stimuli to the discharge of ADH. Abnormalities in reception of stimuli to ADH release, and in the impaired synthesis and release of ADH, are reviewed in relation to the causes of diabetes insipidus, and information on the biochemical changes which have been described in patients with nephrogenic diabetes insipidus is also discussed. We summarize the pathologic lesions and associated diseases found in 54 of our patients with diabetes insipidus. Criteria for establishing the diagnosis of diabetes insipdus are reviewed with emphasis on the dehydration test, including the importance of measuring plasma osmolality at the conclusion of water deprivation. Treatment of diabetes insipidus is briefly discussed with emphasis on the use of DDAVP and oral agents. The syndrome of inappropriate ADH secretion (SIADH) is reviewed including our experience with 39 patients. The differential diagnosis of SIADH, including the value of water loading and the measurement of ADH levels, is discussed. We comment on treatment of these patients including the use of investigational drugs. Lastly, we review the pharmacologic features and clinical relevance of some drugs which alter the release and action of ADH.