Imperial Collage Healthcare

Renin Activity


Test Background

Renin is an aspartyl protease enzyme secreted by the juxto-glomerular cells located in the afferent arterioles of the kidney. It is important in control of production of angiotensin II, a vasoactive peptide that is the principal regulator, along with potassium, of aldosterone release from the adrenal glands. Renin activity is the predominant regulator of aldosterone synthesis and secretion


Clinical Indications

Diagnosis of and differentiation between primary and secondary hyper- and hypo-aldosteronism Monitoring mineralocorticoid replacement therapy Management of renal artery stenosis (RAS) Diagnosis and location of renin-secreting tumours


Reference Range

Less than six years = appropriate range will be given with the test results
Adult (random) = 0.5-3.5 nmol/L/h
Aldosterone to renin ratio used in clinical context to support/exclude diagnosis of primary hyperaldosteronism


Sample Required
EDTA plasma preferred, heparin plasma also accepted

Samples should ideally be separated and frozen within 60 mins but must be separated within 4 hours


Turnaround Time

4 weeks


Notes

The aldosterone renin ratio is used in the clinical context to support/exclude diagnosis of primary hyperaldosteronism. For primary hyperaldosteronism, correct severe hypokalaemia (plasma potassium should be ≥ 3.0 mmol/L). Patients must be receiving an adequate intake of both sodium (100-150 mmol/24 h) and potassium (50-100 mmol/24 h) and discontinue the supplementation temporarily for 24 hours before blood samples are taken. All interfering drugs should be discontinued if at all possible for a minimum of 2 weeks (aldosterone antagonists for 6 weeks). If not possible, antihypertensive drugs may be continued for an initial screening sample with the exception of spironolactone and oestrogen (stop for at least 4 weeks), β-blockers and NSAIDs (stop for at least 1 week).


 

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