Proteinuria in hospitalised internal medicine adult patients

Dipstick proteinuria may be a sign of a renal disorder, false-positive or associated with acute disease, and consequently, transient in hospitalised patients.

To assess (a) the prevalence of proteinuria in hospitalised patients; (b) its association with estimated glomerular filtration rate (eGFR), findings known to cause false-positive test results and indicators of acute disease and (c) the need for follow-up after discharge.

All patients who had a dipstick urinalysis on admission to medical wards of a 400-bed regional hospital in 2018-2019.

Proteinuria.

(a) Other findings on dipstick urinalysis; (b) patients' age, gender, presence of urinary catheter and eGFR and (c) white blood cell count (WBC) and fever.

Of 22 329 patients, 6609 (29.6%) had urinalysis. Of those, 2973 patients (45.0%) had proteinuria of ≥+1 (≥0.30 g/L). The variables independently associated with proteinuria were other dipstick findings known to cause false-positive test results, elevated WBC, fever on presentation, presence of a urethral catheter and a low eGFR. eGFR alone was a poor predictor of proteinuria (c-stat 0.62); however, addition of the remaining independent variables to the model significantly improved its predictive ability (c-stat 0.80).

Dipstick proteinuria is common in hospitalised patients. Although weakly associated with eGFR, proteinuria is mainly associated with confounding factors that may result in false-positive test results. The need for follow-up of proteinuria after discharge has questionable clinical utility and its high frequency would entail a considerable cost.