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Albuminuria and Proteinuria Aldosterone, Endogenous 1303

• Use of plasma samples. If heparinized/EDTA Relative Cost: $ • Other than dehydration, high albumin is
anticoagulated plasma is substituted, values Pearls • If hypoalbuminemia is detected by human
not associated with specific disease states.
VetBooks.ir Specimen Collection and Handling • Concentrations may be slightly lower in very AUTHOR: Mary Leissinger, DVM, MS, DACVP
may be higher from nonspecific binding of
the reagent bromocresol green to globulins.
lab, repeat test in veterinary lab.
young and in geriatric patients.
formulate differential diagnoses and clinical
Serum (red top tube). Heparinized or EDTA • Interpret together with serum globulins to EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
anticoagulated plasma may be substituted. workup for abnormal values.

Albuminuria and Proteinuria

Definition Causes of Abnormally High Levels Specimen Collection and Handling
The detection and estimation of protein and Proteinuria can be divided into four major Clean urine collection container; midstream
albumin present in the urine. categories grouped based on origin: (1) prerenal, catch, catheterized sample, or cystocentesis
(2) glomerular, (3) tubular, and (4) hemorrhagic can be used. Microalbuminuria measured via
Synonym(s) or inflammatory (postrenal) (p. 1444). point-of-care kit or as mail-out test.
Urine protein quantification, microalbuminuria
testing, bumintest Next Diagnostic Steps to Consider Relative Cost: $
if Levels Are High
Physiology • Examine urine sediment for evidence of Pearls
• Small proteins (<68,000 kDa) may pass hemorrhage and/or inflammation. • Urine protein should always be interpreted
through the glomerular filtration barrier or • Rule out muscle damage (elevated CK in light of the urine specific gravity, pH
may be normal mucoproteins secreted by >20,000) or hemolysis (serum). values, and sedimentation findings (inactive
the renal tubules (Tamm-Horsfall proteins). • Measure serum proteins (hyperproteinemia, sediment: absence of pyuria and hematuria).
• Albumin, produced by the liver, is the hyperglobulinemia, or hypoalbuminemia). • Trace results on dipstick in concentrated
main oncotic force within the vasculature. • If Bence Jones proteinuria is suspected, con- urine (>1.025) are common.
Because of its molecular weight (approxi- sider urine or serum protein electrophoresis. • Cloudy urine should be ultracentrifuged
mately 66-70 kDa) and charge, albumin is • Urine protein/creatinine ratio (p. 1391) before performing SSA testing.
minimally filtered through the glomeruli • Microalbuminuria is more sensitive and
and is thus preserved within the vasculature Drug Effects specific for albuminuria than is dipstick assay.
during health. The small amount of albumin • Dipstick method: falsely increased from ○ Microalbuminuria is not unique to glo-
filtered at the glomerulus is reabsorbed in quaternary ammonium salts or chlorhexidine merular disease and should be interpreted
the proximal tubules via pinocytosis. • SSA testing: increased from X-contrast media, in the context of the clinical presentation.
• Proteinuria and albuminuria can be measured tolbutamide, penicillin (large dose), sulfisoxa- ○ It may be useful as a screening/monitoring
in several ways. zole, tolmetin sodium, and co-precipitation tool in breeds predisposed to protein-losing Laboratory Tests
of crystals. nephropathy (PLN) or in the presence of
Reference Interval disease that predisposes to PLN before
• Wet chemistry instrument methods: Lab Artifacts overt proteinuria is recognized.
4-95 mg/dL protein • Dipstick method falsely increased
• Urine dipstick: negative, trace, 1+ (30 mg/ ○ Highly buffered alkaline urine (>8.0) or AUTHOR: Erin N. Burton, DVM, MS, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
dL), 2+ (100 mg/dL), 3+ (>300 mg/dL) in highly concentrated and moderately
• SSA turbidity test: this method detects alkaline urine
albuminuria and Bence Jones proteins ○ Pigmenturia or abnormal urine color may
better than globulins. Results are assessed interfere with reagent color interpretation.
on a turbidity scale; 1 to 4+ • SSA testing
• Microalbuminuria: ELISA and nephelometric ○ Decreased from highly buffered alkaline
assays; detects albumin at concentrations urine
< 30 mg/dL

Aldosterone, Endogenous

Definition Physiology Reference Interval
Aldosterone is a mineralocorticoid hormone Aldosterone is released by the zona glomerulosa • Dogs: 14-957 pmol/L (resting); 197-
produced by the adrenal gland that is an integral in response to angiotensin II promoting the 210 pmol/L3 (post–ACTH stimulation)
part of the renin-angiotensin system that reabsorption of sodium, accompanied by water • Cats: 194-388 pmol/L (resting); 277-
regulates water homeostasis and blood pressure. in exchange for potassium, at the level of the 721 pmol/L (post–ACTH stimulation)
Endogenous aldosterone concentrations deter- kidney (mainly distal tubules).
mine the amount of circulating aldosterone.

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