Background: To evaluate serum antidiuretic hormone (ADH), its receptors, and renin levels in cerebral salt wasting (CSW) in tuberculous meningitis (TBM).

Methods: Patients diagnosed with definite (n = 30) or probable TBM (n = 47) who developed hyponatremia (CSW, SIADH, or miscellaneous causes) were included. Sequential measurement of serum ADH, ADH-R, and renin activity by enzyme-linked immunosorbent assay was done and correlated with serum sodium level, urinary output, and fluid balance.

Results: Out of 79 TBM patients, CSW was observed in 36, SIADH in four, and miscellaneous hyponatremia in eight patients. CSW patients had a longer hospital stay (P < 0.001), lower GCS score (P < 0.007), higher MRC grade (P < 0.007), and a lower serum Na (P < 0.001) compared to non-CSW TBM patients. In severe CSW patients, serum ADH and ADH-R were correlated with hyponatremia and returned to baseline on correction; however, serum renin levels remained elevated. Serum ADH was related to hyponatremia but ADH-R and renin were not. ADH-R and renin levels did not significantly differ in CSW and SIADH.

Conclusions: CSW is the commonest cause of hyponatremia in TBM and correlates with disease severity. ADH is related to hyponatremia, but ADH receptor and renin are not.