• Clinical science

Diagnostic evaluation of the kidney and urinary tract


Diseases of the kidney and the urinary tract can present with a wide array of symptoms. In addition to flank or groin pain, referred pain may occur in other regions of the body, which can make diagnosis difficult. Therefore, acute abdominal pain requires consideration of the kidneys and urinary tract. Most chronic renal diseases are asymptomatic and are only detected through abnormal findings on urinalysis (erythrocytes, protein) or pathological changes of renal function parameters (increased serum creatinine, blood urea nitrogen). An ultrasound can be used for a quick evaluation of the kidney and urinary tract and is critical in diagnosing urinary tract obstructions and urinary retention.

Physical examination

Acute appendicitis should be differentiated from right-sided renal colic! Appendicitis often presents with nausea, fever, and pain at McBurney's point!


  • Quantity of urine
    • Polyuria: urine output > 3 L/day in adults
    • Oliguria: urine output < 500 mL/day
    • Anuria: urine output < 50 mL/day
  • Quality of urine
    • Isosthenuria: loss of the ability to concentrate or dilute urineurine osmolality approaching that of plasma
    • Glycosuria: glucose in the urine
    • Proteinuria: > 150 mg protein/day in the urine
    • Leukocyturia/pyuria: white blood cells in the urine, sometimes with visible cloudiness
    • Bacteriuria: ≥ 105 organisms/mL organisms (in midstream collection)
    • Hematuria (see below)
    • Hemoglobinuria: hemoglobin in the urine
    • Myoglobinuria: myoglobin in the urine
Most likely diagnosis
Glycosuria Diabetes mellitus
Bacteriuria Urinary tract infection
Hematuria in the first or last part of micturition Urethral damage
Persistent hematuria Vesical or supravesical origin
Painless hematuria Malignancy
Hemoglobinuria Severe intravascular hemolysis
Myoglobinuria Rhabdomyolysis
Polyuria Diabetes mellitus, diabetes insipidus, drinking excessive amounts of water



Glomerular hematuria Nonglomerular hematuria
Color (macroscopic) Red, smoky brown, “Coca-Cola” Red or pink urine
Clots Absent Sometimes present
RBC morphology Dysmorphic Normal (isomorphic)
RBC Casts Sometimes present Absent
Proteinuria > 500 mg/day < 500 mg/day


Blood values


Renal biopsy





Differential diagnosis