The prevalence of hypercalcemia in patients with untreated tuberculosis (TB) varies widely between countries. Since the vitamin D status and calcium intake are important determinants of hypercalcemia in TB, these two factors were compared among four populations (U.K., Hong Kong, Malaysia, Thailand) with a low prevalence (<3%) and two populations (Sweden, Australia) with a high prevalence (>25%). In the three Asian countries, the circulating vitamin D levels are abundant, but the calcium intakes are low. Subjects from the U.K. have the lowest circulating vitamin D level of all, although their calcium intake is high. In Sweden and Australia, both the circulating vitamin D levels and calcium intakes are high. Since serum 1,25(OH)2D concentration will only be raised if its substance for extrarenal conversion, 25(OH)D, is plentiful and the effect of a given serum 1,25 (OH)2D concentration on serum calcium is determined by the calcium intake, it is postulated that the regional variation in the prevalence of hypercalcemia in TB may be due to differences in the circulating vitamin D levels and calcium intakes in these populations.
In this study we examined the incidence of hypercalcaemia among patients with tuberculosis in Malaysia. Serum calcium concentration and other calcium metabolism parameters were studied in 43 newly diagnosed tuberculous patients from the Kuala Lumpur General Hospital and the National Tuberculosis Centre. Forty-four patients admitted to the medical wards of the General Hospital, Kuala Lumpur were recruited as controls. The incidence of hypercalcaemia was found to be only 1/43 (2.3%). There was no significant difference between the mean serum calcium and other calcium metabolism parameters between the patients and the controls. Despite earlier reported incidences of 30-50%, this study showed that hypercalcaemia in tuberculosis is uncommon in Malaysia.
A retrospective six-month study of serum calcium and albumin in patients treated at the Kuala Lumpur Hospital was carried out. There were 19,291 subjects, of which the prevalences of hypocalcemia (corrected serum calcium of < or = 2.1 mmol/l) and hypercalcemia (corrected serum calcium of > 2.7 mmol/l) were 18.0% (3460 subjects) and 2.4% (468 subjects) respectively. Persistent hypocalcemia (a minimum of first two consecutive corrected serum calcium of < or = 2.1 mmol/l) was found in 408/19,291 subjects 2.1%). Serum calcium values of < 2.00 mmol/l were found in 98.5% of this group. Persistent hypercalcemia (a minimum of first two consecutive corrected serum calcium of > 2.7 mmol/l) was found in 108/19,291 subjects (0.5%) and 52/108 subjects (48.1%) had serum calcium values of > or = 3.0 mmol/l. 2902/3460 subjects (83.8%) and 313/468 subjects (66.9%) the hypocalcemia and hypercalcemia groups respectively failed to be retested (singletons). In the hypocalcemia group, 1115/2902 (38.4%) showed corrected serum calcium values of < 2.00 mmol/l), whilst 100/313 subjects (31.9%) of the hypercalcemia group had corrected serum calcium values of > or = 3.00 mmol/l. There were no significant differences between the mean corrected serum calcium between 3 age groups of the test population, namely in childhood ( < or = 65 years).