What is the likely cause of left-sided flank pain in a 33-year-old male with a history of daily exercise, who presents with clear and yellow urine, and no symptoms during voiding, and is being treated with Voltaren (Diclofenac) cream for suspected muscular-related pain?

From the Guidelines

I strongly recommend against ordering a KUB x-ray as the initial diagnostic test for this patient, and instead suggest a noncontrast CT abdomen and pelvis, as it is the most appropriate imaging modality for evaluating suspected urolithiasis, according to the most recent evidence 1. The patient's symptoms of left-side flank pain, absence of urinary symptoms, and daily workout routine suggest muscular strain as a possible cause. However, to rule out kidney stones, a noncontrast CT abdomen and pelvis is the preferred imaging modality, as it can detect renal stones without the use of IV contrast, which may obscure small stones 1. Additionally, a noncontrast CT can also help diagnose other causes of abdominal pain. I recommend applying Voltaren cream (diclofenac sodium) to the affected left flank area three to four times daily for muscular pain relief, as it can help reduce inflammation locally in the muscle tissue by inhibiting prostaglandin synthesis 1. Massage a small amount (about the size of a quarter) into the painful area until absorbed, and continue this regimen for 7-10 days, but discontinue if skin irritation occurs. If pain persists beyond a week, worsens significantly, or if the patient develops fever or urinary symptoms, please return for reassessment as this could indicate a different underlying condition. Some key points to consider when evaluating this patient include:

• The patient's symptoms are more consistent with muscular strain, likely from daily workouts
• The absence of urinary symptoms makes kidney stones less likely, but a noncontrast CT abdomen and pelvis can help rule this out
• Voltaren cream can provide effective pain relief for muscular strain
• If the patient's symptoms worsen or change, further evaluation and reassessment may be necessary.

From the FDA Drug Label

In a European retrospective population-based, case-controlled study, 10 cases of oral diclofenac associated drug-induced liver injury with current use compared with non-use of diclofenac were associated with a statistically significant 4-fold adjusted odds ratio of liver injury Inform patients of the warning signs and symptoms of hepatotoxicity (e.g., nausea, fatigue, lethargy, diarrhea, pruritus, jaundice, right upper quadrant tenderness, and "flu-like" symptoms). To minimize the potential risk for an adverse liver-related event in patients treated with diclofenac sodium topical solution, use the lowest effective dose for the shortest duration possible The patient will be prescribed Voltaren cream to alleviate muscular-related pain, but it is crucial to monitor liver function and inform the patient of the warning signs of hepatotoxicity. The patient should be treated with the lowest effective dose for the shortest duration possible to minimize the risk of adverse liver-related events 2.

From the Research

Patient Presentation

• The patient is a 33-year-old male presenting with left-side flank pain and lower back pain.
• He works out every day and is concerned about a kidney stone.
• The patient's urine is clear and yellow with no odor, and he denies any symptoms when voiding.

Diagnostic Approach

• A KUB x-ray has been ordered to evaluate for kidney stones, despite the lack of symptoms related to kidney stones.
• The patient's symptoms and presentation may not be typical of nephrolithiasis, as suggested by the study 3, which highlights the importance of considering other differential diagnoses in patients with flank pain and hematuria.
• The use of unenhanced CT, as recommended by the study 4, may be a more effective imaging modality for evaluating acute flank pain and determining the presence or absence of ureteral obstruction.

Imaging Considerations

• The study 5 emphasizes the importance of minimizing radiation exposure in patients with nephrolithiasis, particularly those with recurrent stones.
• Low-dose noncontrast computed tomography is recommended as the gold standard of imaging for patients with acute renal colic, especially those with a body mass index of < 30.
• The study 6 demonstrates the accuracy of unenhanced helical CT performed at reduced radiation doses, which may be a suitable alternative for patients with suspected nephrolithiasis.

Treatment and Management

• The patient has been prescribed Voltaren cream to alleviate muscular-related pain.
• The study 7 highlights the importance of advances in radiology and percutaneous therapy in improving care for patients with urinary tract stones.
• Dual-energy CT may enable more accurate characterization of stone disease and direct therapy at the time of the initial imaging evaluation, as suggested by the study 7.