Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Abstract

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

Impact of Surgical Factors on Delayed Hyponatremia in Patients With Nonfunctioning Pituitary Adenoma After Endonasal Endoscopic Transsphenoidal Procedure

“…In the present study, transient DI occurred in 35.5% of the delayed hyponatremia cases and in 8.5% of cases with normal natremia, while multivariate analysis showed that transient DI was signi cantly correlated with delayed hyponatremia (OR 6.21, p = 0.001) as was meningitis (OR 12.03, p = 0.006). These results were compatible with previous reports noting that hyponatremia following DI was caused by SIADH due to unregulated released of AVP from denervated posterior pituitary nerve terminals [29,33].…”

First Reported Case of Reverse Pott’s Disease

“…Hyponatremia also has a similar prevalence (45%) in TB meningitis patients [ 12 ]. In TB meningitis cases, both SIADH and cerebral salt wasting have been noted to be the cause of hyponatremia [ 13 ].…”

The association between serum sodium level and tuberculous meningitis compared with viral and bacterial meningitis

“…The association between hyponatremia and TBM has been elucidated and is well-known 8 , 14 . In one study including 76 cases of TBM, hyponatremia was observed in approximately 45% of the cases 12 .…”