A patient saw the "Salt Must Die" billboards and slashed their intake, assuming it was a public health campaign.

Pseudohypercreatininemia

Via the Renal Fellow Network:

In the Jaffe reaction, creatinine reacts with picric acid to form a colored complex. This forms the basis for the commonest methods for measuring serum creatinine. However, this test has well known limitations. Under normal circumstances, the Jaffe reaction overestimates the serum creatinine concentration by 10-20% because of the presence of endogenous chromogens. These chromogens include acetone and acetoacetate which, in the case of diabetic ketoacidosis, can lead to a significant overestimation of the serum creatinine. Similarly, certain drugs, including cephalosporins, flucytosine and barbiturates, can interfere with the assay.