What is the role of lab testing in the evaluation of contrast-induced nephropathy (CIN)?

Updated: Dec 18, 2018
  • Author: Anita Basu, MD, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

In contrast-induced nephropathy (CIN), the serum creatinine (SCr) concentration usually begins to increase within 24 hours after contrast agent administration, peaks between days 3 and 5, and returns to baseline in 7-10 days. Serum cystatin C (which has been suggested as a surrogate marker of renal function in lieu of SCr) is increased in patients with CIN.

Nonspecific formed elements can appear in the urine, including renal tubular epithelial cells, pigmented granular casts, urate crystals, and debris. However, these urinary findings do not correlate with severity.

Urine osmolality tends to be less than 350 mOsm/kg. The fractional excretion of sodium (FENa) may vary widely. In the minority of patients with oliguric CIN, the FENa is low in the early stages, despite the absence of clinical evidence of volume depletion.


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