Interpreting Urine Laboratory Findings
| Disease | Cause | Laboratory Findings | Signs | Chemical Findings | Microscopic Findings |
|---|---|---|---|---|---|
| Acute glomerulonephritis | Anti–basement membrane antibodies associated with strep infection, variety of infectious agents, toxins, allergens | Rapid appearance of hematuria, proteinuria, and casts | Gross hematuria, turbid, smoky | Protein <1.0 g/dL Blood positive | Increased RBCs, WBCs, renal tubular epithelial |
| Inflammation of the glomeruli by which they become abnormally permeable and leak plasma proteins and blood into the renal tubules | Varying degree of hypertension, renal insufficiency, and edema Frequently seen in children and young adults | Casts: RBCs, granular, waxy, broad | |||
| Chronic glomerulonephritis | Represents end-stage result of persistent glomerular damage with continuing and irreversible loss of kidney function | Symptoms include edema, hypertension, anemia, metabolic acidosis, oliguria progressing to anuria | Hematuria | Protein >2.5 g/dL Blood, small amount SG low and fixed | Increased RBCs, WBCs, renal epithelial Casts: granular, waxy, broad |
| Progresses to end-stage kidney disease | |||||
| Nephrotic syndrome | Glomeruli whose basement membrane has become highly permeable to plasma proteins of large molecular weight and lipids, allowing them to pass in the tubules | Massive protein, edema, high levels of serum lipids, and low levels of serum albumin | Cloudy | Protein >3.5 g/dL Blood, small amount | Increased RBCs, oval fat bodies, free fat, renal epithelial Casts: fatty, waxy, renal |
| Acute tubular necrosis | Destruction of renal tubular epithelial cells | Oliguria and complete kidney failure | Slightly cloudy | Protein <1.0 g/dL Blood positive | Increased RBCs, WBCs, renal epithelial |
| Usually following a hypotensive event (shock), toxic element, or drugs and heavy metals | SG low | Casts: renal, granular, waxy, broad | |||
| Cystitis (lower urinary tract) | Infection of the bladder most commonly caused by bacteria; Escherichia coli most common (85%) | Frequent and painful urination | Cloudy, foul smelling | Protein <0.5 g/dL Blood, small amount | Increased WBCs, bacteria, RBCs, transitional epithelial |
| Urethritis (urethra in males) | Nitrite positive (usually) Leukocyte esterase positive (usually) | ||||
| Acute pyelonephritis (upper urinary tract) | An infection of the kidney or renal pelvis | More frequently in women with repeated urinary tract infections | Turbid, foul smelling | Protein <1.0 g/dL Blood positive | Increased WBCs (clumps), bacteria, renal epithelial |
| Caused by infectious organism that has traveled through the urinary tract and invaded the kidney tissue | Nitrite positive (usually) Leukocyte esterase positive (usually) | Casts: WBCs, granular, renal, occasionally waxy | |||
| Chronic pyelonephritis | Permanent scarring of the kidney tissue | Polyuria and nocturia develop as tubular function is lost | Cloudy | Protein <2.5 g/dL Nitrite positive (usually) Leukocyte esterase positive (usually) SG low | Increased WBCs Casts: granular, waxy, broad |
| With disease progression, there is hypertension and altered renal and glomerular flow | |||||
| Acute interstitial nephritis | Inflammation of the renal interstitium caused by drug toxicity or an allergic reaction | Fever, eosinophilia Skin rash | Cloudy | Protein <1 g/dL Blood positive Leukocyte esterase positive (usually) | Increased WBCs, RBCs, eosinophils, epithelial Increased casts: granular, renal hyaline |
RBC, red blood cell; SG, specific gravity; WBC, white blood cell.
Adapted from FinneganK. (1998). Routine urinalysis. In LehmannC. A. (Ed.), Saunders manual of clinical laboratory science. WB Saunders.