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Creatinine is commonly used as an approximation of GFR. Creatinine clearance corrected for surface area is approximately 40 mL/min/1.73 M2 in the full term newborn.
GFR increases during the first 2 years of life more rapidly than body size and reaches adult norms/1.73 M2 at the end of this time. Subsequently GFR and body size increase proportionately and thus GFR/1.73 M2 remains stable.
Plasma creatinine concentration alone is not an adequate measure of renal function. Maximum urinary concentrating capacity is less in the newborn; 600-700 milliosmoles/kg water in the full-term newborn, and approximately 400 milliosmoles/kg water in seven month gestation newborns. Maximum urinary concentration of 1200-1400 mOsm/kg water is characteristically achieved in children by
Hematuria
Clinical Evaluation of Hematuria
Physical Examination. Height, weight, blood pressure, optic fundi, presence or absence of mass, skin appearance, genitalia, edema, complete physical examination.
Laboratory. Urinalysis, urine culture, CBC, serum BUN, creatinine, calcium, streptozyme, serum complement (Cs as screen), quantitative urinary protein, calcium and creatinine, nephrosonogram.
Differential Diagnosis of Red Urine
Red Urine, No Blood Present on Dipstick, No Red Cells on Microscopic Examination
Hematuria not present
Red color is probably caused by dyes or
Hematest Positive, No RBC on Microscopic Examination
Hemoglobinuria
Glucose-6-phosphate dehydrogenase deficiency
Paroxysmal hemoglobinuria
Mismatched blood transfusion
Fresh water drowning
RBC present on microscopic examination, but No casts: Exercise, fever, sickle hemoglobin, hypercalciuria, stones, familial, coagulopathy, trauma, drugs (eg, Cytoxan), tumors, cysts, hydronephrosis, interstitial nephritis, lower urinary tract infection.
Microscopic Hematuria with Casts, but No Proteinuria
IGA nephropathy: Proliferative glomerulonephritis (familial or non-familial)