Abstract
Delayed hyponatraemia(DH) is a common complication following trans-sphenoidal
surgery(TSS) for pituitary tumour. We evaluated the prevalence of DH following
TSS, and assessed the factors associated with DH, including early post-operative
diabetes insipidus(EPDI). This retrospective study included 100 TSS for
pituitary tumours in 98 patients, over a period of 26 months. Subjects were
divided into two groups: those who developed hyponatraemia and those who did not
develop hyponatraemia, during post-operative days 4 to 14. The clinical
characteristics and peri-operative parameters were compared between the two
groups, to identify factors predicting DH. The mean age of the patients was
42.0±13.6 years, 58 (59%) were females and 61 (61%) had
functional tumours. Thirty-six patients(36%) developed DH following TSS
of whom majority(58%) were diagnosed on post-operative days 7 and 8;
only 8/36 (22%) were symptomatic. Syndrome of inappropriate
antidiuretic hormone secretion(SIADH) was found to be the most common aetiology
of DH. On logistic regression analysis, intra-operative cerebrospinal fluid(CSF)
leak (OR 5.0; 95% CI 1.9–13.8; p=0.002), EPDI (OR 3.4;
95% CI 1.3–9.2; p=0.015) and peri-operative steroid use
(OR 3.6; 95% CI 1.3–9.8; p=0.014) were found to be
significantly associated with DH. In conclusion, EPDI, intra-operative CSF leak
and peri-operative steroid use were significant predictors of DH. EPDI predicts
moderate to severe hyponatraemia with 80% specificity but has low
sensitivity(47%). As most patients have asymptomatic hyponatraemia,
serum sodium measurement on POD 7 to 10 would be helpful to identify DH in
patients at increased risk.
Key words
hyponatraemia - post-operative diabetes insipidus - SIADH - cerebrospinal fluid leak - pituitary tumour
