Protein:creatinine ratio in random urine samples is a reliable marker of increased 24-hour protein excretion in hospitalized women with hypertensive disorders of pregnancy.
BACKGROUND
The protein:creatinine ratio in random, untimed urine samples correlates with 24-h protein excretion in pregnant women with and without hypertension. Nevertheless, whether this ratio is appropriate as a screening test for proteinuria is still unclear, in part because of the paucity of large studies.


METHODS
We measured protein:creatinine ratios in random urine samples and protein contents of 24-h urine samples in a cross-sectional study of 927 hospitalized pregnant women at >/=20-weeks of gestational age and in a 2nd cohort of 161 pregnant women. In the 2nd group, urine specimens were obtained before and after completion of the 24-h collections, avoiding 1st-morning void specimens.


RESULTS
Protein excretion was >/=300 mg/24 h in 282 patients (30.4%). The urine protein:creatinine ratio and the 24-h protein excretion were significantly correlated (r = 0.98, P <0.001). The protein:creatinine ratio as an indicator of protein excretion >/=300 mg/24 h was >/=0.3. The sensitivity and specificity were 98.2% and 98.8%, respectively. Positive and negative predictive values were 97.2% and 99.2%, respectively, and positive and negative likelihood ratios were 79.2 and 0.02, respectively. The diagnostic accuracy of the urinary protein:creatinine ratio was corroborated in the 2nd cohort of patients, which also showed no statistically significant difference in protein:creatinine ratio between samples obtained >24 h apart.


CONCLUSIONS
Random urinary protein:creatinine ratio is a reliable indicator of significant proteinuria (>300 mg/day) in nonambulatory pregnant women, irrespective of sampling time during the daytime. The protein:creatinine ratio may be reasonably used as an alternative to the 24-h urine collection method.
Research Unit in Reproductive Medicine and Hypertensive Diseases of Pregnancy Clinic, Hospital de Ginecología y Obstetricia "Luis Castelazo Ayala", Instituto Mexicano del Seguro Social, México, D.F. México. alfredolm@yahoo.com
Alfredo
A
Leaños-Miranda
Janeth
J
Márquez-Acosta
Fernando
F
Romero-Arauz
Guadalupe M
GM
Cárdenas-Mondragón
Roxana
R
Rivera-Leaños
Irma
I
Isordia-Salas
Alfredo
A
Ulloa-Aguirre
D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000652:urine*; D005260:Female; D006760:Hospitalization; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000175:diagnosis* / Q000652:urine; D011247:Pregnancy; D011507:Proteinuria / Q000175:diagnosis* / Q000652:urine; D013997:Time Factors
D015415:Biomarkers; D003404:Creatinine