The best way to detect elevated albuminuria.
BACKGROUND
It has been reported that first morning specimens are more reliable than random spot specimens to assess 24-hour urinary albumin excretion rate (UAER), especially if albuminuria is expressed as albuminuria to creatininuria ratio. We aimed to investigate the influence of (a) posture and activity and (b) the units to best estimate 24-hour albuminuria.


METHODS
In this retrospective study, 24-hour UAER was compared to 60 min 'supine' and 90 min 'activity' albuminuria in 124 patients tested for resistant hypertension. The ability to adjust urinary albumin concentration (UAC) to creatininuria (ACR) or to collection duration (tAER) values in order to increase the reliability of albuminuria values was also analyzed.


RESULTS
Compared to 24-hour UAER, UAC (mg/l), tAER (μg/min) and ACR (mg/mmol) during the supine period had a similar concordance rate in normo-, micro- and macroalbuminuric patients. The UAC in the supine period was well related to 24-hour UAER. However, UAC almost doubled during activity. Adjustment to creatininuria improved the correlation between albuminuria during both periods and 24-hour UAER, but mainly during the activity period.


CONCLUSIONS
Our results confirm that UAC is dependent on physical activity. Correction of UAC by creatininuria (ACR) provides a satisfactory estimation of 24-hour UAER. Thus, for practical reasons, it is advisable to use ACR, where no differences appear to exist, whether a supine urine sample or an activity urine sample is obtained.
Department of Nephrology and Hypertension, Groupement des Hôpitaux Sud, Hospices Civils de Lyon and Claude Bernard University, Lyon, France.
Abbas
A
Deeb
Aoumeur
A
Hadj-Aissa
Michel
M
Ducher
Colette
C
Chapuis-Cellier
Jean-Pierre
JP
Fauvel
D000328:Adult; D000419:Albuminuria / Q000175:diagnosis* / Q000652:urine*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000652:urine; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D012189:Retrospective Studies; D016683:Supine Position / Q000502:physiology*; D013997:Time Factors; D016482:Urinalysis / Q000379:methods / Q000592:standards