Reference — Renal
Urinalysis Interpretation Reference
Comprehensive urinalysis interpretation — physical characteristics (color, clarity, odor), chemical dipstick components, microscopic examination (casts, cells, crystals), and clinical significance for UTI diagnosis, AKI classification, and glomerular disease identification.
Reference · Renal
Educational use only. Urinalysis results must be interpreted in clinical context. Dipstick findings should be confirmed with culture or microscopy when clinically significant. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Urine Color Interpretation
| Color | Likely Meaning | Conditions / Causes |
|---|---|---|
| Pale yellow / straw | Normal / well-hydrated | Normal hydration; may be pale in high fluid intake or dilute urine (DI) |
| Dark yellow / amber | Concentrated urine — dehydration | Dehydration, fluid restriction; normal when first void of morning |
| Orange | Concentrated + possible bile pigments | Severe dehydration, obstructive jaundice (bilirubin), medications (rifampin, phenazopyridine) |
| Pink / red | Hematuria OR medications/food | Gross hematuria (UTI, glomerulonephritis, kidney stone, tumor), myoglobinuria (rhabdomyolysis), hemoglobinuria; beets, rifampin, phenazopyridine (AZO) can cause red-orange color WITHOUT blood |
| Brown / tea-colored / cola-colored | Myoglobin, hemoglobin, or bilirubin | Rhabdomyolysis (myoglobinuria — brown + dipstick positive for blood without RBCs on microscopy), severe hemolysis (hemoglobinuria), post-streptococcal GN ('cola-colored'), liver disease (bile pigments) |
| Green / blue-green | Bile, bacteria, medications | Pseudomonas UTI, biliverdin from liver disease, propofol (rarely), methylene blue, amitriptyline |
| Cloudy / turbid | Pyuria, bacteriuria, phosphaturia, crystals | UTI (WBCs + bacteria), phosphaturia (normal in alkaline urine after meals), contamination |
| Foamy / frothy | Proteinuria | Persistent foam = significant proteinuria (nephrotic syndrome, diabetic nephropathy). Transient foam after forceful voiding may be normal. |
Chemical Dipstick Interpretation
pH
Normal: 4.5–8.0 (average 5–6)
Alkaline urine (pH > 7): UTI with urease-producing organisms (Proteus, Klebsiella), renal tubular acidosis, vegetarian diet, post-meal alkaline tide. Acidic urine (pH < 5.5): DKA (ketones), uric acid stones, high-protein diet, acidosis.
Specific gravity
Normal: 1.003–1.030
HIGH (> 1.025): dehydration, SIADH, ADH effect. LOW (1.001–1.003): diabetes insipidus, excessive water intake, renal tubular disease. Fixed 1.010: isosthenuria = CKD (tubules can't concentrate or dilute). Concentrated urine = dehydrated; dilute = overhydrated or tubular dysfunction.
Protein
Normal: Negative or trace
POSITIVE: glomerular damage (nephrotic syndrome: 3+ to 4+; nephritic: 1+ to 2+). AKI (tubular damage). UTI (inflammation). Orthostatic proteinuria (benign — only positive when upright). Dipstick detects albumin primarily — false negative for Bence-Jones protein (multiple myeloma). Confirm with 24h urine protein or spot protein:Cr ratio.
Glucose
Normal: Negative
POSITIVE (glucosuria): serum glucose exceeds renal threshold (~180 mg/dL) — diabetes mellitus. Pregnancy (lower renal threshold). Renal glycosuria (Fanconi syndrome — tubular defect). Positive urine glucose does NOT directly equal blood glucose — check serum.
Ketones
Normal: Negative
POSITIVE: diabetic ketoacidosis (DKA — large ketones), starvation/fasting, alcoholic ketoacidosis, low-carbohydrate diet. Important DKA monitoring marker (along with blood glucose and anion gap).
Blood
Normal: Negative
POSITIVE: hematuria (RBCs), myoglobinuria (rhabdomyolysis — dipstick positive, microscopy shows NO RBCs — key differentiator), hemoglobinuria (hemolysis). Dipstick cannot distinguish — microscopy required. Hematuria + proteinuria + RBC casts = glomerulonephritis.
Nitrites
Normal: Negative
POSITIVE: gram-negative bacterial UTI (E. coli, Klebsiella, Proteus convert nitrates to nitrites in urine). DOES NOT detect gram-positive organisms (Enterococcus, Staphylococcus saprophyticus) — these are nitrite-negative UTIs. Requires bacteria in urine ≥ 4h (daytime sample less sensitive — first morning void best).
Leukocyte esterase
Normal: Negative
POSITIVE: WBCs in urine (pyuria) — UTI or urethritis. Used with nitrites: both positive = very likely UTI. Leukocyte esterase positive + nitrite negative = possible gram-positive UTI, contamination, or sterile pyuria (TB, renal stone, chlamydia urethritis).
Bilirubin
Normal: Negative
POSITIVE: conjugated (direct) hyperbilirubinemia — hepatocellular disease (hepatitis, cirrhosis), obstructive jaundice (bile duct obstruction). Unconjugated bilirubin (hemolysis) is NOT excreted in urine — negative. Positive urine bilirubin = liver or biliary tract problem.
Urobilinogen
Normal: 0.2–1.0 mg/dL (small amount normal)
ELEVATED: increased RBC destruction (hemolytic anemia), hepatocellular disease (liver not clearing urobilinogen from portal circulation). ABSENT: complete biliary obstruction (no bile reaching intestine = no urobilinogen formed).
Urine Cast Identification
Casts form in the distal tubule and collecting duct from Tamm-Horsfall protein. Their composition reflects what was in the tubule at time of formation. They are always pathological except hyaline casts in small numbers.
| Cast Type | Composition | Clinical Significance |
|---|---|---|
Hyaline casts Normal or non-specific | Tamm-Horsfall protein only — no cells | NORMAL in small numbers (0–2/LPF). Increased with dehydration, strenuous exercise, concentrated urine, mild renal stress. Not pathological in isolation. |
RBC casts Critical — glomerulonephritis | Red blood cells embedded in protein matrix | PATHOGNOMONIC for glomerulonephritis — only glomerular bleeding produces RBC casts. Critical diagnostic finding. Also seen in vasculitis, SBE. |
WBC casts Upper urinary tract infection or interstitial nephritis | White blood cells embedded in protein matrix | Indicates renal parenchymal inflammation: pyelonephritis, interstitial nephritis, or glomerulonephritis (with inflammation). Key: pyelonephritis vs cystitis distinction — WBC casts confirm upper tract (renal) involvement. |
Granular casts (coarse/fine) Tubular injury — non-specific | Degraded cellular debris; tubular cells | Non-specific tubular injury. Present in various renal diseases. Progression: cellular → granular → waxy casts as injury advances. |
Muddy brown casts Critical — acute tubular necrosis (ATN) | Tubular epithelial cell debris (granular casts with brown pigment) | HALLMARK of acute tubular necrosis (ATN) — most common cause of intrarenal AKI. Associated with ischemia (sepsis, hypotension) or nephrotoxins (aminoglycosides, contrast, cisplatin, rhabdomyolysis). |
Waxy casts Advanced/chronic renal disease | Advanced cellular degeneration (far downstream from granular) | Indicates severe, advanced chronic kidney disease (very slow urine flow allows full cast degeneration). Also called 'renal failure casts' — seen in ESRD. |
Fatty casts / oval fat bodies Nephrotic syndrome | Lipid-laden tubular cells or free lipid droplets | PATHOGNOMONIC for nephrotic syndrome — lipiduria results from massive proteinuria and hyperlipidemia. Oval fat bodies appear as cells with lipid vacuoles. |
Broad / waxy casts Chronic renal failure / ESRD | Very wide casts formed in dilated collecting ducts | Indicate CKD with tubular atrophy and dilatation. Wide because formed in greatly enlarged tubular segments. Also called 'renal failure casts.' |
Rhabdomyolysis — Key UA Distinction
Dipstick positive for blood + Microscopy shows NO RBCs = Myoglobinuria (Rhabdomyolysis)
The dipstick detects heme groups in both RBCs AND myoglobin — it cannot distinguish. If the dipstick is 3+ for blood but microscopy shows <3 RBCs/HPF, myoglobinuria is the explanation. Check CK levels (markedly elevated in rhabdomyolysis: >1000 U/L, often >5000 U/L). Urine appears brown/tea-colored. AKI follows from tubular toxicity. Treatment: aggressive IV fluid resuscitation (target UO 200–300 mL/hr).
NCLEX Pearls
RBC casts = glomerulonephritis — only glomerular bleeding produces these casts. Pathognomonic.
WBC casts = upper UTI (pyelonephritis) — distinguish from lower UTI (cystitis has WBCs in urine but NO casts).
Muddy brown casts = ATN (acute tubular necrosis) — intrarenal AKI from ischemia or nephrotoxins.
Fatty casts / Maltese cross = nephrotic syndrome — massive proteinuria + hyperlipidemia → lipiduria.
Waxy casts = advanced CKD / ESRD (also called renal failure casts).
Nitrites positive = gram-negative UTI (E. coli). Nitrite-negative with positive leukocyte esterase = possible gram-positive UTI or contamination.
Blood positive on dipstick but no RBCs on microscopy = myoglobinuria (rhabdomyolysis). Check CK levels.
AZO (phenazopyridine) turns urine orange-red — does NOT cause positive blood on dipstick. Interferes with nitrite and leukocyte esterase readings.
Foamy/frothy urine = significant proteinuria — nephrotic syndrome until proven otherwise.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with KDIGO Clinical Practice Guidelines · National Kidney Foundation (NKF). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →