Laboratory Examination• -clean midstream catch is usually

adequate• -in children,urine can be collected by

placing a urine collection bag over the urethral meatus

Examination of urine

• urinary pH• specific gravity• protein• glucose• ketones• bilirubin• urobilinogen• hemoglobin, leukocytes, and nitrites

relies on color changes produced by chemical reactions with substances in the urine

Examination of Urine

• pH - will reflect the pH of the serum

• Specific gravity – reflects the hydration status of the patient and the

concentrating ability of the kidney• Proteinuria – indicate intrinsic renal pathology or the presence of excess

protein in the serum. • Glucose and Ketones – screening for diabetes– greater than 180 mg/dL

Examination of Urine• Bilirubin and high levels of

Urobilinogen– liver disease or hemolysis.

• Hemoglobin, myoglobin, and red blood cells – can produce a positive result on

dipstick tests for blood.

• Leukocytes and nitrites – inflammation, which is most

commonly caused by a bacterial infection.

• Leukocyte esterase, – an enzyme found in neutrophils

Urine Culture

• Greater than 105 organisms/mL – UTI

• 100 organisms/mL of a known urinary pathogen – bacterial infection

• Antibiotic sensitiviy testing

Tests for Kidney Function• Specific gravity– with a progressive decrease in renal function, the

specific gravity does not decrease below approximately 1.015.

• Creatinine clearance– volume of plasma from which creatinine is

completely removed per unit of time and is a clinical approximation of the glomerular filtration rate (GFR) and renal function

– Clearance=UV/P– N: 90 to 110 mL/min

Tests for Kidney Function

• Gold standard for measuring GFR – Inulin is an ideal substance for measuring GFR

because it is completely filtered by the kidney without being secreted or reabsorbed by the tubules.

– Vs.Creatinine • Secreted in small amounts by the proximal tubule.

Therefore, creatinine clearance will slightly overestimate GFR at all levels of kidney function.

• This effect is most pronounced when kidney function is severely compromised, where creatinine clearance can overestimate GFR by as much as 1.5- to twofold.