Urinalysis
25/11/10
PY Mindmaps
Examinations Book
Visual inspection
- yellow: normal
- pale/clear: diuretics, diabetes insipidus
- milky: lipiduria, UTI
- pink/opalescent: haemoglobinuria
- pink/cloudy -> red: haematuria
- tea coloured: myoglobinuria, metronidazole, porphyria
- blue: methylene blue administration
- green: propofol toxicity
- orange: rifampicin, conjugated bilirubin
- grey/black: homogentisic acid in alkaptonuria, melanogens in disseminated melanoma,
Addisons disease
Dipstick
- specific gravity: normal 1.003-1.030, increased: hyperglycaemia, proteinuria, SIADH,
intravascular dehydration, radiocontrast, deceased: DI, GN, pyelonephritis, renal failure
- pH: normal 4.5-8, < 6: acidosis and pre-renal failure, >7: alkalosis and alkalinising agents,
RTA
- glucose: hyperglycaemia or renal glycosuria
- blood: positive in haematuria, haemoglobinuria, myoglobinuria
- protein: albuminuria (requires further investigation – GN, MM, malignancy, pyelo)
- BHCG: pregnancy status
- WCC: pyuria
- nitrites: bacterial infection (most convert nitrates to nitrite)
- ketones: starvation, diabetic or alcoholic ketoacidosis, carbohydrate free and high
fat+protein diet
- bilirubin and urobilinogen: conjugated -> excess production or biliary obstruction,
urobilinogen -> absent in biliary obstruction
Microscopy
CELLS
-
RBC: renal disease (low specificity), dysmorphic cells -> GN
WCC: infection (low specificity), renal calculi, interstitial nephritis, GN, vasculitis, infarction
tubular cells: tubular disease
eosinophils: interstitial nephritis
CASTS
-
hyaline: can be normal
red cell casts: glomerular disease (GN), endocarditis
white cell casts: pyelonephritis, interstitial nephritis, vasculitis, infarction
granular: non-specific to many renal parenchymal disease
fatty: diabetic nephropathy and nephrotic syndrome
Jeremy Fernando (2010)
- epithelial: recovery phase of ATN
- eosinophilia: interstitial nephritis and atheroembolism
CRYSTALS
- oxalate crystals: ethylene glycol poisoning
- calculi: calcium, magnesium-ammonium-phosphate, urate, cysteine
- drugs: sulphonamides, methotrexate, acyclovir, radiocontrast
Electrolytes
SODIUM
- increased loss: hypoadrenalism, salt-losing nephropathy, ATN, excess salt loads, SIADH
- decreased loss: hyperaldosteronism, Cushing’s syndrome, intravascular dehydration, prerenal failure, hepatorenal syndrome
POTASSIUM
- helps clarify whether loss is renal or extra-renal
- increased loss: hypomagnesaemia, ATN, loop and thiazide diuretics, hyperaldosteronism,
Cushings syndrome, amphotericin B
CHLORIDE
- may help clarify the mechanism of metabolic alkalosis
- UrCl- <10mmol/L: intravascular volume depletion (diuretics, vomiting)
- UrCl- >10mmol/L: intravascular volume expansion + hypokalaemia (hyperaldosteronism)
CALCIUM
- may clarify deranged calcium homeostasis
- increased loss: loop diuretics, idiopathic hypercalcuria, hypoparathyroidism, vitamin D
intoxication, renal failure, RTA, sarcoidosis
- decreased excretion: hyperparathyroidism, malabsorption syndromes, vitamin D deficiency,
thiazide diuretics
OSMOLARITY
- like Na+ is a marker of hydration and concentration ability but also reflects excreted
osmotically active substances (ie. mannitol, radiocontrast, glucose)
URINARY CYSTATIN C
- predictor of severity of acute tubular dysfunction in a range of renal pathologies.
Jeremy Fernando (2010)