MATERIALS AND METHODS: Retrospective data were obtained for 36 patients with CKD stage 4 and 5 after parathyroid surgery, correlating albumin-corrected serum calcium with the infusion rate of calcium gluconate. Calcium flux was characterised along with excursions out of the target calcium range of 2 to 3 mmol/L. With this data, an improved titration regimen was constructed.
RESULTS: Mean peak efflux rate (PER) from the extracellular calcium pool was 2.97 mmol/h occurring 26.6 hours postoperatively. Peak calcium efflux tended to occur later in cases of severe POH. Eighty-one per cent of patients had excursions outside of the target calcium range of 2 to 3 mmol/L. Mean time of onset for hypocalcaemia was 2 days postoperatively. Hypocalcaemia was transient in 25% and persistent in 11% of patients.
CONCLUSION: A simple titration regimen was constructed in which a 10% calcium gluconate infusion was started at 4.5 mL/h when serum calcium was <2 mmol/L, then increased to 6.5 mL/h and finally to 9.0 mL/h if calcium continued falling. Preoperative oral calcium and calcitriol doses were maintained. Blood testing was done 6-hourly, but when a higher infusion rate was needed, 4-hourly blood testing was preferred. Monitoring was discontinued if no hypocalcaemia developed in the fi rst 4 days after surgery. If hypocalcaemia persisted 6 days after surgery, then the infusion was stopped with further monitoring for 24 hours.
MATERIALS AND METHODS: A total of 3,175 adult University Malaya Medical Centre (UMMC) patients deemed free of any calcium metabolism disorders were selected and divided into two groups for derivation and validation. Simple linear regression associating total calcium and albumin was constructed from the data in the derivation group. The new albumin-adjusted calcium equation was validated in the validation group. Differences in calcium status classification following adjustments based on existing and new albumin-adjusted calcium equation was compared in a 469 hypoalbuminaemic patients.
RESULT: The new albumin adjusted calcium equation was: total calcium + 0.014 x (39-albumin). Of the 469 hypoalbuminemic patients, 78 were classified differently based on new equation. Based on the new equation, 55 normocalcemic patients were classified as hypocalcemic and 22 were classified as normocalcemic instead of hyperclacaemic.
CONCLUSION: Based on the newly derived albuminadjusted calcium equation 17% of patients had different adjusted calcium classifications. This could potentially impact in the management. It is recommended that laboratories derive equations specific to their calcium/albumin methods and analytical platforms.
OBJECTIVES: (1) Evaluate the four published equations' performance in estimating ionised calcium; (2) Determine the accuracy of calculated ionised and adjusted total calcium in classifying patients according to calcium states; and (3) Identify factors associated with hypocalcaemia in the critically ill population.
MATERIALS AND METHODS: This is a cross-sectional study involving 281 critically ill patients aged 18-80 years of both genders in a Malaysian tertiary intensive care unit. Performance of the four equations was analysed using Bland-Altman difference plot and Passing Bablok regression analysis. Crosstabulation was conducted to assess classification accuracy. Mann-Whitney U or Pearson Chi-Square tests were performed to identify variables associated with hypocalcaemia.
RESULTS: Calculated ionised calcium using all four equations significantly overestimated ionised calcium. Calculated ionised and adjusted total calcium had poor accuracies in classifying hypocalcaemic patients. pH was significantly higher in hypocalcaemics.
CONCLUSION: Calculated ionised and adjusted total calcium significantly overestimate ionised calcium in the critically ill. In this specific population, calcium status should only be confirmed with ionised calcium measured by direct ion-selective electrode (ISE).
DESIGN: Serum intact parathormone (PTH) concentrations were measured on samples taken before and during a variable-rate tri-sodium citrate infusion designed to 'clamp' the whole blood ionised calcium concentration 0.20 mmol L-1 below baseline for 120 min.
SUBJECTS: Six Malaysian patients aged 17-42 years with acute malaria, four of whom were restudied in convalescence, and 12 healthy controls aged 19-36 years.
MAIN OUTCOME MEASURES: Whole-blood ionised calcium and serum intact PTH concentrations.
RESULTS: The mean (SD baseline ionised calcium was lower in the malaria patients than in controls (1.09 +/- 0.06 vs. 1.18 +/- 0.03 mmol L-1, respectively; P = 0.01) but PTH concentrations were similar (3.0 +/- 1.8 vs. 3.3 +/- 1.3 pmol L(-1); P = 0.33). Target whole-blood ionised calcium concentrations were achieved more rapidly in the controls than the patients (within 15 vs. 30 min) despite significantly more citrate being required in the patients (area under the citrate infusion-time curve 0.95 (0.25 vs. 0.57 +/- 0.09 mmol kg-1; P < 0.01). The ratio of the change in serum PTH to that in ionised calcium (delta PTH/ delta Ca2+), calculated to adjust for differences in initial rate of fall of ionised calcium, was similar during the first 5 min of the clamp (132 +/- 75 x 10(-6) vs. 131 +/- 43 x 10(-6) in patients and controls, respectively, P > 0.05), as were steady-state serum PTH levels during the second hour (7.0 +/- 2.2 pmol L-1 in each case). Convalescent patients had normal basal ionised calcium levels but the lowest serum intact PTH levels before and during the clamp, consistent with an increase in skeletal PTH sensitivity after treatment.
CONCLUSIONS: There is a decreased ionised calcium 'set point' for basal PTH secretion but a normal PTH response to acute hypocalcaemia in malaria. Skeletal resistance may attenuate the effects of the PTH response but patients with malaria appear relatively resistant to the calcium chelating effects of citrated blood products.
EVIDENCE ACQUISITION: We conducted a meta-analysis to evaluate the relationship between primary aldosteronism (PA) with bone biochemical markers and to assess bone mineral density in patients with primary aldosteronism.
EVIDENCE SYNTHESIS: A total of 939 subjects were examined (37.5% with PA). Patients with PA had significantly higher serum parathyroid hormone, lower serum calcium, higher urine calcium excretion and higher serum alkaline phosphatase compared to patients without PA, with no significant difference in serum vitamin D between both groups. Bone mineral density of lumbar spine, femoral neck and total neck of femur were similar between two groups. With PA treatment, there was a significant increment in serum calcium and reduction in serum parathyroid hormone.
CONCLUSIONS: PA is associated with hypercalciuria with subsequent secondary hyperparathyroidism. This potentially affects bone health. We recommend this to be part of complication screening among patients with PA.
METHODS: Data from 549 subjects from the Malaysian Aging Male Study, which included Malay and Chinese men aged 20 years and older residing in the Klang Valley, were used for analysis. The subjects' calcaneal speed of sound was measured, and their blood was collected for biochemical analysis. Two sets of multiple regression models were generated for the total/bioavailable testosterone and estradiol to avoid multicollinearity.
RESULTS: The multiple regression results revealed that bioavailable testosterone and serum total calcium were significant predictors of the calcaneal speed of sound in the adjusted model. After adjustment for ethnicity and body mass index, only bioavailable testosterone remained significant; the total serum calcium was marginally insignificant. In a separate model, the total testosterone and sex hormone-binding globulin were significant predictors, whereas the total serum calcium was marginally insignificant. After adjustment for ethnicity and body mass index (BMI), the significance persisted for total testosterone and SHBG. After further adjustment for age, none of the serum biochemical determinants was a significant predictor of the calcaneal speed of sound.
CONCLUSION: There is a significant age-dependent relationship between the calcaneal speed of sound and total testosterone, bioavailable testosterone and sex hormone-binding globulin in Chinese and Malay men in Malaysia. The relationship between total serum calcium and calcaneal speed of sound is ethnicity-dependent.
METHODS: Predialysis CKD patients were included in this cross-sectional study. Patient demographics, medical/medication histories, and laboratory parameters (serum 25-hydroxyvitamin D (25(OH)D), creatinine, phosphate (P), calcium, albumin, and intact-PTH (i-PTH)) were collected and compared among patients with various CKD stages. The association between 25(OH)D and these parameters was determined by multiple linear regression.
RESULTS: A total of 196 patients with mean ± SD eGFR of 26.4 ± 11.2 mL/min/1.73 m2 was included. Vitamin D deficiency (25(OH)D concentration < 15 ng/mL) and insufficiency (25(OH)D concentration 16 - 30 ng/mL) was found in 29.1% and 57.7% of the patients, respectively. Mean ± SD serum 25(OH)D was 20.8 ± 9.3 ng/mL. Female patients had lower vitamin D concentrations than males (16.9 ng/mL vs. 23.9 ng/mL; p < 0.001). Vitamin D levels were also higher in Chinese (22.3 ng/mL) than Malay (17.3 ng/mL) and Indian (13.1 ng/mL) patients (p < 0.05). Nonadjusted analyses showed higher i-PTH concentration in vitamin D deficient patients (p < 0.05).
CONCLUSION: Despite being a sun-rich country all year round, the majority (86.8%) of predialysis CKD patients in Singapore have suboptimal vitamin D status. Lower vitamin D concentrations were found in females and in those with darker skin tone. Vitamin D deficient patients also tended to have higher i-PTH levels.