It is preferred that 24 hour urine calciums are collected into a bottle containing 10 mL of 8N HCl as preservative (2 mL for small children). If just tests that require acidification are requested, preservative 10mL 8N HCl is added. If other chemistries requested, do not use HCl.
24 hour urine containers can be collected from the Pathology. When collecting a container, the request slip is required so that we are able to determine what (if any) additives are required.
NB. Acid is corrosive and the bottle should be labelled with a corrosive label.
APPLICATION: Usually for investigation of renal calculi. Diagnosis of hypocalcuric hypercalcaemia.
INTERPRETATION: Increased excretion is seen with high dietary intake of calcium, increased mobilisation of calcium from bone, and most conditions associated with hypercalcaemia. Hypercalcuria is a risk factor for renal calculi.