Plain urine. First morning or timed overnight urine
First morning samples: A urine albumin of > 20 mg/l with a urine albumin/creatinine ratio of > 2.5 mg/mmol is suggestive of microalbuminuria
Timed overnight specimens: A urine albumin excretion rate (AER) of > 20 µg/min with a urine albumin/creatinine ratio of > 3.0 mg/mmol indicates microalbuminuria.
Microalbumin is a test currently used only in diabetics where it is a marker for early nephropathy at a stage where it is reversible with good control of hypertension and hyperglycaemia. In Type 2 diabetes, it is a powerful risk marker for vascular disease.
The term microalbumin refers to ordinary albumin (not a tiny albumin) found in urine at concentrations below 300 mg/L, the cut-off point for conventional urine dipsticks. Concentrations above this are called macroalbuminuria, persistent proteinuria or clinical proteinuria and indicates irreversible nephropathy. Because biological variance of urine microalbumin is high (± 50%) and because transient increases in microalbumin can be due to urinary tract infection, exercise, intercurrent illness etc, a first abnormal result should be followed by others over a 2-12 month period and include an MSU looking for UTI. The possibility of non-diabetic nephropathy also needs to be considered.
Presence of microalbuminuria above 70-100 mg/day in diabetes, particularly Type I, is usually an indication for scrupulous control of even mild degrees of hypertension using an ACE inhibitor as the agent of first choice in most patients.
If the microalbumin concentration is greater than 400 mg/L, the laboratory auto-reflexes a protein/creatinine ratio.
Can be added on to an existing request up to 4 days following sample receiptSpecimen Labelling Procedure