C2 URINALYSIS PART 2

Chemical examinations

pH

Normal pH range : 4.5 - 8.0

pH: Reflects the kidney’s ability to regulate the acid-base balance

• Through regulation of hydrogen ions excretion
• Only reliable when testing on freshly voided specimen
• Influenced by diet and medications

Alkaline urine: pH > 7.0

• due to respiratory/metabolic alkalosis, presence of urease-producing bacteria, renal tubular acidosis, urinary tract infection
• promotes calcium-phosphate precipitation
• vegetarian diet, diets high in citrate, drugs i.e., sodium bicarbonate, potassium citrate and acetazolamide

Acidic urine: pH < 7.0

• diabetes mellitus, diabetes ketoacidosis, diarrhea, emphysema
• promotes the formation of uric acid and cystine kidney stones
• high-protein diet, intake of acidic fruit (eg., cranberries), drugs (eg., ammonium chloride)

Red Blood Cells

Normal: Negative/ less than or equal to 5 RBCs per ml

Hematuria: presence of 3 or more RBCs per high-powered field in 2 of three urine samples
Indications of RBCs in urine

• Tumours / trauma / infections / inflammation in genitourinary tract
• Pyelonephritis, lupus nephritis, kidney stones, renal hypertension
• Non-renal: hemorrhagic disorder, exposure to toxic chemicals, strenuous exercise

White blood cells (WBCs)

Normal: only a few

• Pyuria: excessive amount of WBCs in urine
• less than 5 WBCs per high-powered field is considered abnormal

Indications of WBCs in urine

• Bacterial infection in renal / genitourinary system, i.e., cystitis, pyelonephritis
• Other non-infectious inflammatory disorders, eg., glomerulonephritis & lupus nephritis
• Presence of tumours and renal calculi

Proteins

Normal: only in trace amount ( less than or equal to 150mg/day or 10mg/dL)

Proteinuria (Albuminuria)

• Elevated proteins in the urine
• ~1/3 of the total urinary proteins is albumin
• Other proteins: Tamm-Horsfall mucoproteins (secreted by distal renal tubule), immunoglobulin light chains, microglobulin, etc.

Indications of proteins in urine

• Physiological: strenuous exercise, dehydration
• Renal diseases / failure: eg., nephrosis, glomerulonephritis, polycystic kidney disease
• Systemic disorders leading to increased level of serum proteins: eg., multiple myeloma

Glucose

Normal: negative

• Glycosuria: the presence of reducing sugars (eg., glucose, lactose, galactose, fructose, etc.) in the urine
• Glucosuria: the presence of glucose in the urine; most frequent type of glycosuria
• Plasma glucose level >180-200 mg/dL

Indications of glucose in urine

• Diabetes mellitus, Cushing’s syndrome, Fanconi’s syndrome, liver & pancreatic diseases
• Rare hereditary metabolic disorders (eg., fructosuria, galactosuria)
• Gestational diabetes

Ketone bodies (Ketones)

Normal: negative

• Ketonuria: high level of ketones in the urine

Indications of ketone bodies in urine

• Pregnancy, ketogenic diets, compromised nutritional intake
• Uncontrolled diabetes mellitus (diabetic ketoacidosis), liver disease, certain forms of glycogen storage disease

Bilirubin (conjugated)

Normal: negative

Indications when bilirubin present in urine

• Liver dysfunction (due to obstructive jaundice, cirrhosis, viral- or drug-induced hepatitis, hepatotoxic drugs, toxins)
• Biliary obstruction
• Congenital hyperbilirubinemia

Urobilinogen

Normal: 0.1 mg/dL – 1.0 mg/dL or 4 mg/day

Indications when urobilinogen present in urine

• Increase in hemolysis, hepatocellular disease (eg., cirrhosis, hepatitis), severe infection
• Decrease in bile duct obstruction, renal insufficiency, with antibiotic use

Leukocyte esterase

Normal: negative

Indications when leukocyte esterase present in urine

• Presence of neutrophils, either due to infection or other inflammatory processes, in urinary tract or kidneys

Nitrites

Normal nitrites: negative

Indications when nitrites present in urine

• Presence of a significant number of bacteria, and a urine culture should be performed
• Urinary tract infection caused by nitrate reductase- positive bacteria (eg., E. coli, Enterobacter, Klebsiella, etc.)

Microscopical Examination

Examining the urine sediment for cells, casts, crystals & bacteria

Should be performed among those with persistent hematuria or proteinuria

Requires 10-15 ml of fresh urine specimen to be centrifuged at 1500-3000 rpm for 5 min

Decant the supernatant, resuspend the sediment, transfer a single drop to a clean glass slide and apply cover slip