No need for routine glycosuria/proteinuria screen in pregnant women

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Original Research

No need for routine glycosuria/proteinuria screen in pregnant women

J Fam Pract. 2005 November;54(11):978-983

By

William A. Alto, MD, MPH

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References

1. Graham Center One-Pager. Family physicians’ declining contribution to prenatal care in the United States. NAMCS data. Am Fam Physician 2002;66:2192.-Available at www.aafp.org/afp/20021215/graham.html. Accessed on October 1, 2005.

2. American Academy of Pediatrics and American College of Obstetricians and Gynecologists. Guidelines for Perinatal Care. 5th ed. Washington, DC: ACOG; 2002;90-93.

3. Lind T, Hytten FE. The excretion of glucose during normal pregnancy. J Ob Gyn Brit Commonwealth 1972;79:961-965.

4. Watson WJ. Screening for glycosuria during pregnancy. Southern Med J 1990;83:156-158.

5. Gribble RK, Meier PR, Berg RL. The value of urine screening for glucose at each prenatal visit. Obstet Gyn 1995;85:405-410.

6. Hooper DE. Detecting GD and preeclampsia. J Repro Med 1996;41:885-888.

7. Buhling KJ, Elze L, Henrich W, et al. The usefulness of glycosuria and the influence of maternal blood pressure in screening for diabetes. Eur J Obstet Gynecol Reprod Biol 2004;113:145-148.

8. American Diabetes Association. Gestational diabetes mellitus: position statement. Diabetes Care 2004;27:S88-S90.

9. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin Gestational diabetes. Washington, DC: ACOG; 2001;30:360-372.

10. Institute for Clinical Systems Improvement. Health Care Guidelines: Routine prenatal care. August 2002:14. Available at www.icsi.org. Accessed on June 13, 2004.

11. Bitzen PO, Bengt S. Assessment of laboratory methods for detection of unsuspected diabetes in primary health care. Scand J Prim Health Care 1986;4:85-95.

12. Helton MR, Arndt J, Kebede M, King M. Do low-risk prenatal patients really need a screening glucose challenge test? J Fam Pract 1997;44:556-561.

13. Murray N, Homer CSE, Davis GK, Curtis J, Mangas G, Brown MA. The clinical utility of routine urinalysis in pregnancy: a prospective study. Med J Aust 2002;177:477-480.

14. Saudan PJ, Brown MA, Farrell T, Shaw L. Improved methods of assessing proteinuria in hypertensive pregnancy. Brit J Ob Gyn 1997;104:1159-1164.

15. Brown MA, Buddle ML. Inadequacy of dipstick proteinuria in hypertensive pregnancy. Aust NZ Obstet Gynecol 1995;35:366-369.

16. Waugh JJ, Clark TJ, Divakaran TG, Khan KS, Kilby MD. Accuracy of urinalysis dipstick techniques in predicting significant proteinuria in pregnancy. Obstet Gynecol 2004;103:769-777.

17. Misdraji J, Nguyen PL. Urinalysis: when-and when not-to order. 18. Sabai BM. Pitfalls in diagnosis and management of preeclampsia. effects of an herbal mixture MA-471. Alternat Ther Clin Pract 1996;3:26-31.

18. Sabai BM. Pitfalls in diagnosis and management of preeclampsia. Amer J Ob Gyn 1996;3:26-31.

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21. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin 29. Chronic hypertension in pregnancy. Washington, DC: ACOG; 2001;303-311.

22. Gribble RK, Fee SC, Berg RL. The value of routine urine dipstick screening for protein at each prenatal visit. Am J Obstet Gynecol 1995;173:214-217.

23. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin 33. Diagnosis and management of preeclampsia and eclampsia. Washington, DC: ACOG; 2002;312-320.

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Practice recommendations

Screening for gestational diabetes using urine dipsticks for glycosuria is ineffective with low sensitivities. False-positive tests outnumber true positives 11:1. A 50-g oral glucose challenge is a better test. Tests for glycosuria after this blood test are not useful (B).
Proteinuria determined by dipstick in pregnancy is common and a poor predictor for preeclampsia with a positive predictive value between 2% and 11%. If the blood pressure is elevated, a more sensitive test should be used (B).
After urinalysis at the first prenatal visit, routine urine dipstick screening should be stopped in low-risk women (B).

Abstract

Objective: More than 22 million prenatal visits occur in the US each year.¹ Each pregnant woman averages 7 visits. Most include urine testing for glucose and protein to screen for gestational diabetes and preeclampsia. Is there sufficient scientific evidence to support this routine practice?
Methods: We searched Medline (1966–2004), the Cochrane review, AHRQ National Guideline Clearinghouse, the Institute for Clinical Systems Improvement, and Google, searching for studies on proteinuria or glycosuria in pregnancy. The reference list of each article reviewed was examined for additional studies, but none were identified. We found 6 studies investigating glycosuria as a predictor for gestational diabetes mellitus, or proteinuria as a predictor for preeclampsia (1 examined both). Because every study used different dipstick methods of determining results, or definitions of abnormal, each was evaluated separately.
Results: Glycosuria is found at some point in about 50% of pregnant women; it is believed to be due to an increased glomerular filtration rate.³ The renal threshold for glucose is highly variable and may lead to a positive test result for glycosuria despite normal blood sugar. High intake of ascorbic acid or high urinary ketone levels may result in false-positive results. Four published studies assessed the value of glycosuria as a screen for gestational diabetes.^4-7 All used urine dipsticks. Three of the 4 most likely overestimate the sensitivity of glycosuria for predicting gestational diabetes.
Conclusions: Routine dipstick screening for protein and glucose at each prenatal visit should be abandoned. Women who are known or perceived to be at high risk for gestational diabetes or preeclampsia should continue to be monitored closely at the discretion of their clinician.

Routine dipstick testing is time-consuming and expensive, especially when carried out over multiple visits. False-positive test results are frequent and often lead to further laboratory examinations. Today, when our care of patients is squeezed by both time and monetary constraints, we have a rare opportunity to make office visits more productive and to save patients the burden of unnecessary work-ups.

Review methods

We searched Medline from 1966 to September 2004 for English language articles using keyword searching for “proteinuria” or “glycosuria” and “prenatal” or “pregnancy.” We explored the Cochrane review, AHRQ National Guideline Clearinghouse, the Institute for Clinical Systems Improvement, and Google. The reference list of each article reviewed was examined for additional studies, but none were identified.

All 6 identified studies that investigated glycosuria as a predictor for gestational diabetes mellitus or proteinuria as a predictor for preeclampsia are reviewed in this analysis. One study examined both. Because every study used different dipstick methods of determining results, or definitions of abnormal, each was evaluated separately.

What the evidence shows

Found at some point in about 50% of women, glycosuria is believed to be due to an increased glomerular filtration rate.³ The renal threshold for glucose is highly variable and may lead to a positive test result for glycosuria despite a normal blood sugar. High intake of ascorbic acid or high urinary ketone levels may result in false-positive results. There have been 4 published studies designed to assess the value of glycosuria as a screen for gestational diabetes mellitus.^4-7 All used urine dipsticks (TABLE 1).

FAST TRACK

High ascorbic acid intake or high urinary ketone levels can cause false-positive glycosuria results

Watson: Urine test a poor screening instrument

In an observational prospective study of 500 women, Watson evaluated glycosuria (trace, ≥100 mg/dL) detected on 2 separate prenatal visits (17% of women) as a predictor of gestational diabetes.⁴ Gestational diabetes was defined as an abnormal 50-g glucose screen at 28 weeks gestation confirmed by an abnormal 100-mg 3-hour oral glucose tolerance test (OGTT).

He reported that glycosuria used as a screening test for gestational diabetes had a sensitivity of 27% and a specificity of 83% with a negative predictive value (PV–) of 96% and a positive predictive value (PV+) of 7% in a population with an unusually high prevalence of gestational diabetes of 4.4%. The high prevalence of gestational diabetes in this cohort increased the PV+ of urine screening for glycosuria. Women with severe glycosuria (>250 mg/dL, 2+) on 2 determinations during the first 2 trimesters had a 21% chance (PV+) of being diagnosed as having gestational diabetes.