Differential Diagnosis
The patient's clinical presentation and laboratory findings suggest a renal issue, with several potential diagnoses to consider. Here's a breakdown of the differential diagnosis:
Single most likely diagnosis
- Acute Tubular Necrosis (ATN): The presence of granular casts, renal epithelial cells, and low urine osmolality, combined with the patient's history of acute flank pain and elevated serum creatinine, strongly supports ATN as the most likely diagnosis. ATN can result from ischemia or nephrotoxicity, which could be related to the patient's antihypertensive medications or the episode of acute flank pain.
Other Likely diagnoses
- Prerenal Azotemia: Although the patient's urine osmolality is low, which is not typical for prerenal azotemia, decreased renal perfusion due to antihypertensive medications or other factors could still contribute to the patient's condition.
- Acute Interstitial Nephritis: This condition, often caused by medications or infections, can present with similar laboratory findings, including elevated creatinine and abnormal urine sediment.
- Renal Vascular Disease: The patient's history of hypertension and acute flank pain could suggest renal vascular disease, such as renal artery stenosis or thrombosis, which could lead to renal impairment.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Sepsis: Although not directly suggested by the patient's presentation, sepsis can cause acute kidney injury (AKI) and should be considered, especially in elderly patients with decreased urine output.
- Obstructive Uropathy: Despite the absence of difficulty in voiding, obstructive uropathy (e.g., due to kidney stones or tumors) could still be present and should be ruled out, as it can cause severe kidney damage if left untreated.
- Aortic Dissection or Aneurysm: The patient's acute flank pain could be a symptom of an aortic dissection or aneurysm, which can compromise renal blood flow and lead to AKI.
Rare diagnoses
- Vasculitis: Conditions like ANCA-associated vasculitis or polyarteritis nodosa can cause renal impairment and should be considered, although they are less common.
- Thrombotic Microangiopathy: This rare condition, characterized by thrombosis in small blood vessels, can cause AKI and should be considered in patients with unexplained renal impairment.
- Glomerulonephritis: Although less likely given the patient's presentation, glomerulonephritis (e.g., post-streptococcal or IgA nephropathy) can cause AKI and should be considered in the differential diagnosis.