Before excretory urography, a patient is normally mildly hypovolemic before the test. Which history finding would call for the patient to be well hydrated instead?

• A. Cystic fibrosis
• B. Multiple myeloma
• C. Gout
• D. Myasthenia gravis

Answer: (B)

The important idea here is protecting the kidneys from contrast-induced injury during excretory urography. Iodinated contrast used in this test can worsen kidney function, especially in patients with existing renal vulnerability, so ensuring good hydration helps maintain renal perfusion and dilute the contrast.

Multiple myeloma is especially relevant because it can cause renal impairment through light-chain–related nephropathy and cast formation in the tubules. Even if standard labs look okay, the kidneys may be more susceptible to contrast damage, so a history of multiple myeloma would prompt ensuring the patient is well hydrated before the procedure.

The other conditions don’t carry the same direct implication for contrast nephropathy risk. Cystic fibrosis can lead to dehydration from salt loss, but it isn’t a specific predisposing factor for contrast-related kidney injury in this context. Gout relates to stone risk and uric acid, not the acute renal susceptibility to iodinated contrast. Myasthenia gravis affects neuromuscular transmission and doesn’t influence renal risk with contrast.

So, this history would trigger a plan of optimal hydration to protect the kidneys during the test.