Post total thyroidectomy hypocalcemia: A novel multi-factorial scoring system to enable its prediction to facilitate an early discharge.

CONTEXT

No single factor can predict the occurrence of post total thyroidectomy (TT) hypocalcemia.

AIMS

This study was conducted to look at various factors usually implicated in post TT clinically significant hypocalcemia (CSH) and to develop a scoring system using a combination of these factors to predict CSH.

SETTINGS AND DESIGN

Prospective study, tertiary care center.

MATERIALS AND METHODS

145 patients, who underwent total thyroidectomy for benign goiters and early carcinoma thyroid ( < T2/N0/M0), were included. Age of the patient, presence, or absence of hyperthyroidism, pre-operative levels of serum calcium and 25 OH vitamin D, post-operative iPTH at 8 hours and calcium at 12 hours, intra-operative parathyroid preservation status, and nodule size were studied. CSH prediction score (0 to 8) was designed based on these 8 factors.

STATISTICAL ANALYSIS

SPSS 13 software was used. For comparison between groups' independent samples T-test and Chi-square test was used. Statistical significance was set at P<0.05. A logistic regression analysis model was built to assess the significant predictors.

RESULTS

There were 22 males and 123 females. 64.82% had euthyroid multinodular goiters, 24.82% had toxic MNG, and 10.34% had an early carcinoma of thyroid. 30.34% developed CSH. CSH was observed in patients with low pre-operative calcium (P=0.008), low 25 OH vitamin D (P=0.001), low post-operative iPTH at 8 hours (P=0.001), low serum calcium at 12 hours after surgery (P=0.001) and lesser number of parathyroid identification at surgery (P=0.001). Patient age (P=0.2) and nodule size (P - 0.17) was not significant. Hypocalcemia risk score of > 3 had 91% sensitivity, 84% specificity with a PPV of 71% and NPV of 95%, whereas score of ≥ 4 had 100% specificity and PPV in predicting CSH.

CONCLUSIONS

CSH after TT is multi-factorial, and a combination of factors (Hypocalcemia prediction score > 3) can be used to predict it so as to discharge patients within 24 hours after surgery.