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Prevalence of Microalbuminuria in Dogs

SUMMARY:

Microalbuminuria was present in ~20% of "normal" dogs and >40% of dogs seen at a referral veterinary teaching hospital (CSU).

Microalbuminuria has been reported to be an early indicator of progressive renal disease in humans with hypertension and diabetic nephropathy. The purpose of this study was to ascertain the prevalence of microalbuminuria in dogs. Microalbuminuria was defined as urinary excretion of albumin greater than 1.0 mg/dl but less than 30.0 mg/dl.

Two separate populations were studied. One sample population was derived from clinically normal dogs (n=86) owned by Heska employees. The second sample population was derived from Colorado State University Veterinary Teaching Hospital patients (n=159) presented for routine health screening, elective procedures, as well as evaluation of health problems. Samples were not excluded on the basis of urine sediment findings. Microalbuminuria was quantitated using an antigen capture ELISA.

To account for varying urine concentrations, results were normalized to a specific gravity of 1.010. Of the 86 clinically normal dogs, 68 (79%) had normalized albumin concentrations <1.0 mg/dl, 16 (19%) had normalized albumin concentrations >1.0 mg/dl and <30.0 mg/dl, and 2 (2%) had normalized albumin concentrations >30.0 mg/dl. Of the 159 hospital patients, 112 (70%) were urine protein test strip negative and 51 of the 112 (46%) test strip negative samples had normalized albumin concentrations >1.0 mg/dl. Conversely, 19 of 80 (24%) of samples with <1.0 mg/dl albumin were positive on urine protein test strip (see Table).

Normalized Urine Albumin Concentration (# of samples)	Urine Protein Test Strip Result (n=159)
Normalized Urine Albumin Concentration (# of samples)	Neg. (112)	Trace (20)	1+ (15)	2-4+ (12)
<1.0 mg/dL (80)	61 (54%)	12 (60%)	5 (33%)	2 (17%)
>1.0 and <30.0 mg/dL (58)	49 (44%)	6 (30%)	2 (13%)	1 (8%)
>30.0 mg/dL (21)	2 (2%)	2 (10%)	8 (53%)	9 (75%)

In the two populations examined, prevalence of microalbuminuria (>1.0 mg/dl and <30.0 mg/dl) ranged from 19% to 36%. We conclude that microalbuminuria is prevalent in a significant number (P <0.01) of dogs. Furthermore, use of urine protein test strips for the detection of albuminuria (>30.0 mg/dl) yields a substantial number of false positive results.

Reproduced with permission of the Journal of Veterinary Internal Medicine.