Differential Diagnosis for a 12-year-old boy with intermittent dark urine and exertional fatigue
- Single most likely diagnosis:
- Hematuria due to warfarin therapy: The patient is on daily warfarin for his mechanical heart valve, and the urinalysis shows 3+ blood without evidence of infection or trauma, making warfarin-induced hematuria a likely cause. The absence of other symptoms such as fever, dysuria, or urinary frequency also supports this diagnosis.
- Other Likely diagnoses:
- Nephrolithiasis (kidney stones): Although the urinalysis does not show crystals, it is possible that the stones are not shedding crystals at the time of the test. The patient's symptoms of intermittent dark urine could be consistent with kidney stones, especially if they are causing intermittent obstruction.
- Glomerulonephritis: This condition can cause hematuria, but it often presents with other symptoms such as hypertension, edema, and proteinuria, which are not present in this case.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Bleeding disorder: Although the patient is on warfarin, it is essential to consider other bleeding disorders, such as hemophilia or von Willebrand disease, especially if the warfarin levels are therapeutic.
- Renal vein thrombosis: This is a rare but potentially life-threatening condition that can cause hematuria, especially in patients with a history of nephrotic syndrome or other hypercoagulable states.
- Sickle cell disease or trait: Although less likely, sickle cell disease or trait can cause hematuria, especially if there is evidence of sickling in the urine.
- Rare diagnoses:
- Alport syndrome: A genetic disorder that affects the type IV collagen in the kidneys, ears, and eyes, causing hematuria, hearing loss, and eye abnormalities.
- Goodpasture syndrome: A rare autoimmune disease that causes glomerulonephritis and pulmonary hemorrhage, presenting with hematuria and possibly other symptoms such as cough or shortness of breath.
- Nutcracker phenomenon: A rare condition where the left renal vein is compressed between the aorta and the superior mesenteric artery, causing hematuria and possibly other symptoms such as abdominal pain or varicocele.