Correction for insulin-dependent diabetes in maternal serum alpha-fetoprotein testing has outlived its usefulness

Reconsidering Race Adjustment in Prenatal Alpha-Fetoprotein Screening

OBJECTIVE

Black racial designation is the only race for which adjustment is recommended for maternal prenatal serum alpha-fetoprotein (AFP) screening. The objective of this study is to reevaluate the relationship between maternal race and maternal serum AFP values in prenatal analyte screening.

METHODS

This was a single-center retrospective analysis of patients who underwent prenatal analyte screening between January 2007 and December 2020. Nomograms for raw maternal serum AFP values by gestational age were created and compared between patients identified as "Black" and "non-Black" on the laboratory requisition. Multivariable linear regression models were created to evaluate the relationship among gestational age, maternal weight, and maternal race on maternal serum AFP levels. The new models were compared with the laboratory-derived calculations, which used historically determined race adjustments.

RESULTS

A total of 43,997 patients underwent analyte screening, and 27,710 patients had complete data for analysis. Of these, 6% were identified as Black. Black patients had laboratory blood draws at a mean gestational age of 123 days, compared with 120 days in non-Black patients ( P <.001), and had higher maternal weight (mean 170 vs 161 lbs, P <.001). Nomograms for raw maternal serum AFP values did not differ between Black and non-Black patients ( P =.065). When adjusted for gestational age and maternal weight, no difference in maternal serum AFP values was identified between Black and non-Black individuals ( P =.81).

CONCLUSION

No difference in maternal serum AFP values was identified between Black and non-Black pregnant individuals when adjusted by maternal weight and gestational age at blood draw. These findings suggest that routine race-based adjustment of maternal serum AFP screening should be discontinued.

Laboratory screening and diagnosis of open neural tube defects, 2019 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG)

Open neural tube defects (ONTDs) include open spina bifida (OSB) and anencephaly. These defects are caused by incomplete closure of the neural tube at about 4 weeks of pregnancy. Levels of early second-trimester maternal serum (ms) alpha-fetoprotein (AFP) are sufficiently elevated in affected pregnancies to be used as a population-based screening test. The basic screening methodology was described in the late 1970s and screening programs were active a few years later. By identifying pregnancies with the highest msAFP levels, about 80% of OSB and 95% of anencephaly can be identified as early as 16 weeks gestation. The interpretation of msAFP levels is complicated by the need to consider multiple factors such as gestational age, maternal weight, maternal race, multiple gestations, and more. Testing for AFP and acetylcholinesterase in amniotic fluid and/or identification of the lesion by targeted ultrasound is considered diagnostic of ONTD. When a diagnosis is made, options include termination, surgery after delivery, or in utero surgery, depending on factors such as location and size of the defect, and the presence of any additional anomalies. Screening for ONTD should be performed as part of a comprehensive program linking primary obstetrical care providers, laboratorians, and high-risk clinicians.

Lower alpha fetoprotein and higher risk of hepatocellular carcinoma, study from the type 2 diabetes mellitus patients

AIMS

To explore the association of type 2 diabetes mellitus (T2DM) with hepatocellular carcinoma (HCC) and alpha fetoprotein (AFP).

METHODS

750 patients with T2DM (T2DM group), 800 healthy people (control group) and 501 patients newly diagnosed with HCC were recruited from 2010 to 2016. The HCC patients were further divided into a HCC with T2DM (HCC+DM) group and a HCC without diabetes mellitus (HCC+NDM) group.

RESULTS

The T2DM group had a 12.61% lower geometric mean AFP level than the healthy control group (2.08 vs. 2.38 μg/L, P < 0.001). Of 501 HCC patients, 230 (45.91%) had T2DM. When compared to the HCC+NDM group, the HCC+DM group had a higher negative rate of AFP (55.22% vs. 37.26%, P < 0.001), worse liver function (P = 0.011) and a 64.87% lower geometric mean AFP level (25.71 vs. 73.18 μg/L, P < 0.001). T2DM was significantly associated with the risk of high-grade (grade 3 and 4) HCC (OR = 2.02, 95% CI 1.18-3.44, P = 0.010).

CONCLUSIONS

T2DM was associated with lower AFP level, worse liver function and higher risk of high-grade HCC. We speculated that low AFP levels in diabetics might delay and interfere with HCC diagnosis, leading to higher degree of malignant HCC.

Maternal serum alpha-fetoprotein values in type 1 and type 2 diabetic patients

OBJECTIVE

Maternal serum alpha-fetoprotein (MSAFP) values are reported to be lower in type 1 diabetic patients, and a correction factor is often applied. We sought to determine whether type 2 diabetic patients require the same MSAFP adjustments as type 1 diabetic patients.

STUDY DESIGN

We performed a retrospective review of MSAFP levels from a university laboratory in type 1 and type 2 diabetic patients between July 2000 and August 2006, matched 1:2 with controls. Groups were compared using analysis of variance and Student t testing.

RESULTS

Seventy-seven type 1 and 75 type 2 diabetic patients were compared with 304 controls. Type 1 and type 2 diabetic patients differed significantly from each other and controls before corrections. Diabetic patients were similar to each other, but significantly lower than controls, after weight corrections. These differences were eliminated by a 10% correction factor.

CONCLUSION

Type 1 and type 2 diabetic patients require both weight and diabetes corrections to adjust MSAFP values to nondiabetic levels.

Impact of folic acid fortification in the United States: markedly diminished high maternal serum alpha-fetoprotein values

OBJECTIVE

Folic acid fortification of breads and grains was implemented in the United States in 1998 in an attempt to reduce the incidence of neural tube defects. Outcome data from birth registries have shown a 20% drop-less than originally predicted. In this study, we ascertain if the impact of folic acid fortification is better seen at the time of midtrimester prenatal diagnosis by looking at incidence of high maternal serum alpha-fetoprotein (MSAFP) values.

METHODS

Data regarding MSAFP levels in 61,119 patients undergoing maternal serum screening at a large commercial laboratory were categorized by multiples of the median (MoM). The data were compared between 2 groups: before mandatory supplementation in the United States in 1997 and after mandatory supplementation in 2000. High MSAFP values were further categorized as high (2.75-4.00 MoM) or very high (more than 4.00 MoM). Data were analyzed by chi(2) analysis.

RESULTS

Comparative data showed a 32% decrease of patients with MoM greater than 2.75 + (2.5% -1.7%). Further categorizations revealed similar decreases.

CONCLUSION

The introduction of folic acid fortification has produced a profound decrease in the number of high MSAFP values, reflective of a decreased incidence of neural tube defects. Our results help to validate the decision to fortify food with folic acid, which represents a highly successful public health policy for primary prevention of birth defects.

LEVEL OF EVIDENCE

II-2

Strict glycemic control in diabetic pregnancy?implications for second-trimester screening for Down syndrome

OBJECTIVES

Studies in the early 1990s showed that the normal levels of the biochemical markers used to screen for Down syndrome in the second trimester of pregnancy differ between healthy women and women with insulin-dependent diabetes mellitus (IDDM). Thereafter, most laboratories adopted correcting factors to adjust for these differences. However, the current validity of these factors in light of the recent improvements in glycemic control in diabetic pregnancy has not been investigated.

METHODS

The sample consisted of 35 pregnant women with strictly controlled IDDM and 40 healthy controls matched for age and gestational week. All women had singleton pregnancies and were followed till delivery.

RESULTS

Comparison of the triple test results between the two groups after adjustment with the traditional corrective factors yielded no significant differences in serum levels of any of the markers (unconjugated estriol, human chorionic gonadotrophin, alpha-fetoprotein).

CONCLUSIONS

These results suggest that the recent improvement in glycemic control of pregnant women with IDDM changes the metabolic milieu that might cause the biochemical differences with healthy pregnant patients.