High prevalence of cholelithiasis in primary hyperparathyroidism: a retrospective analysis of 120 cases.

Primary hyperparathyroidism (PHPT) due to parathyroid adenoma is the most common cause of hypercalcemia, which is characterized by high parathyroid hormone (PTH) level despite elevated serum calcium levels [1]. With the advent of autoanalyzer and serum calcium is a part of routine screening in West. The presentation of PHPT is asymptomatic and hence, attention has been diverted to the features like hypertension, mental changes, peptic ulcer disease and gallstone disease [2, 3]. Few studies have shown the association of cholelithiasis with PHPT [4, 5]. Hypercalcemia and elevated PTH have been implicated as a cause for cholelithiasis in patients with PHPT. This retrospective study was conducted by the Endocrinology department at our institution. PHPT was diagnosed based on elevated calcium and PTH levels. Patients with hyperparathyroidism due to secondary and tertiary causes were excluded. Cholelithiasis was diagnosed by either ultrasonographic evidence of gallstone(s) and/or history of cholecystectomy. Prevalence of cholelithiasis in PHPT patients was compared with that in the normal north Indian population using a study [6] conducted by the Gastroenterology and Hepatology department of our institution. Serum calcium (reference range [RR]: 8.5–10.2 mg/dL), phosphate (RR: 3.5–5 mg/dL), alkaline phosphatase (RR 28–129 IU/L), and creatinine (RR: 0.5–1.4) were measured by standard methods. Serum iPTH (RR: 15–65 pg/mL) was measured by chemiluminescence assay and vitamin D (RR: 9–37 ng/mL) by radioimmunoassay (RIA) using commercially available kits. SPSS 10® software was used to analyze the data. Continuous variables were described as mean (SD) and categorical data were expressed in n (%). Correlation analysis was used to correlate two variables. P<0.05 was considered as statistically significant. One hundred and twenty patients (mean [SD] age 39 [14] years, 80 women) with PHPT were studied. Eightythree patients were below 50 years of age. Their mean weight was 55.1 (14.6) kg and mean BMI 20.8 (4.7) kg/m. All PHPT patients were symptomatic with the most common presenting symptom being bone pain (n=68, 56.7%). Fiftyfour (45.4%) patients had renal stones. The mean serum calcium level was 11.5 (1.8) mg/dL, phosphorus 2.9 (0.8) mg/dL, alkaline phosphatase 217.0 (489.4) IU/L (median 316), vitamin D 25.8 (27.8) (median 15.2) ng/mL and iPTH 819 (700) pg/mL (median 818). Thirty-one patients had cholelithiasis (25.8%). Cholelithiasis was more frequent in women (26 vs. 5) as compared to men; the prevalence in women increased with advancing age (Table 1). Overall the prevalence of gallstones in the reference published study [6] was 3.1% in healthy northern Indian population, and was higher among women (4.2%). After standardization of rates of gallstones for gender, the proportion of gallstones was 2.89% in the reference study, and was 21.24%. (p<0.04) in the present study. No correlation between preoperative serum calcium (r=0.042, p=0.66), phosphate (r=−0.07, p=0.42) and PTH (r=0.03, p=0.7) was seen with cholelithiasis. Using unconditional logistic regression analysis, the only factor that predicted development of gallstone was age (odds ratio −1.05, 95% CI −0.99–1.11, p=0.02). This study showed high prevalence of cholelithiasis in PHPT (25.8%) compared to the general population (3.1%) S. K. Bhadada (*) :A. Bhansali :V. N. Shah :M. Ravikiran : R. Santosh Department of Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India e-mail: [email protected]