Intervention and outcomes
SEPARATION
The procedure was explained to the participants who met the inclusion criteria. All participants signed informed written consent. Subsequently, 5 ml of venous blood was taken to determine serum levels of 25(OH)D and calcium. These blood samples were then transferred to a laboratory affiliated with TUMS, centrifuged (2,500 rpm for 5 min), serum separation was performed and the samples were immediately frozen at -70 °C. ELISA and a kit from EUROIMMUN, a UK manufacturing company measured 25(OH)D. This kit’s mean internal and external variation coefficient was 4.9 and 7.8%, respectively, and the optimum level of 25(OH)D, 30–50 ng/ml was determined based on the information of this kit. Cresolphthalein complexone (CPC) and the Kate method were used to measure serum calcium levels by a Pars Company in Iran. This kit’s mean internal and external variation coefficient was 1.45% and 1.66%, respectively, and the desired calcium level was 8.6–10.3 mg/dl, based on the data of this kit.As guided by the Lasco study (2012) [