Laboratory Medicine

Specimen Handling

Patient preparation: Patient should liberalize (not restrict) sodium intake. The following medications should be held for 4 weeks prior to testing or for as long as is clinically feasible: spironolactone, eplerenone, amiloride, triamterene, potassium-wasting diuretics, confectionary licorice, or chewing tobacco. Please refer to the 2016 Endocrine Society Practice Guidelines for more information (Funder et al., J Clin Endocrinol Metab 2016).

Collection Instructions: Collect 1 lavender (EDTA) and 1 gold top tubes. Collect blood midmorning, after the patient has been up (sitting, standing, or walking) for at least 2 hours and then seated for 5-15 min. State whether the patient was supine or upright when the blood was drawn. Write your initials, date and time of collection on the collection label or requisition.

Laboratory Staff Instructions: Separate 2 aliquots (1 plasma and 1 serum) and freeze immediately. Referred-in specimens must arrive at SMH core lab frozen. Avoid refrigeration for >4 hours to eliminate cryoactivation of prorenin to renin. Store sample in assigned rack -30 freezer by the separation bench.

Add-on stability: Cannot add on to a previous sample draw.

Rejection Criteria: Heparinized plasma and thawed samples.

Stability: Sample stable refrigerated for 4 hours and frozen for 30 days.

Transportation: In-house: Transport at room temperature ASAP. Referred-in: Store and send specimens frozen to SMH core lab.