Prevalence of vitamin D deficiency in uninsured women.

BACKGROUND: Vitamin D deficiency, an important risk factor for osteoporosis and other chronic medical conditions, is epidemic in the United States. Uninsured women may be at an even higher risk for vitamin D deficiency than others owing to low intake of dietary and supplemental vitamin D and limited sun exposure. OBJECTIVE: Our goal was to determine the prevalence of vitamin D deficiency in this vulnerable population. SETTING AND PARTICIPANTS: We enrolled 145 uninsured women at a County Free Medical Clinic in urban Michigan. Questionnaires were used to obtain information about demographics, medical history, vitamin supplementation, sunlight exposure, and dietary vitamin D intake. RESULTS: The 96 women who were tested for vitamin D status ranged in age from 21 to 65 years (mean 48 +/- 11), and 67% were vitamin D deficient as indicated by a 25-hydroxyvitamin D [25(OH)D)] level <50 nmol/L (20 ng/mL). Non-Caucasians were 3 times more likely than Caucasians to be vitamin D deficient (P = .049). Mean dietary vitamin D intake was low (125 +/- 109 IU/d) and only 24% of the participants used any supplemental vitamin D. Participants with total vitamin D intake <400 IU/day from diet and supplements were 10 times more likely to be vitamin D deficient than others (P < .001). CONCLUSIONS: These results demonstrate a high prevalence of vitamin D deficiency in an uninsured, medically underserved female population. Uninsured women should be strongly encouraged to increase their vitamin D intake.

Standardization of methods reduces variability: explanation for historical discrepancies in biochemical screening.

Over the past decade, many studies have argued the relative merits of different chromosome abnormality biochemical screening protocols in different labs. Results and interpretations have varied markedly (e.g., double vs. triple screening). In this study we sought to compare coefficients of variation (CV) among 12 laboratories in one system, using identical and different methodologies for the three parameters. Ten identical specimens were processed as part of the 1999 College of American Pathologists (CAP) (FP-A, FP-B) proficiency tests. Results were compared among 12 laboratories using the Abbott ELISA for alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), and two methods for estriol [Diagnostic Services Laboratory (DSL) and an "in house" assay]. The range on the 10 specimens of means for AFP varied from 12.56 to 117.87; hCG 14.05-68.08; and estriol 0.61-2.73. CV for AFP specimens averaged 10%, hCG 8%, and estriol 35% (F = 22.4). However, when only DSL was used for estriol, the CV was reduced to 8.7%. Standardization of AFP and hCG across 12 labs has reduced CV to <10%, which is similar to accepted between run results. Wide variation of uE3 among different methods may explain the widely divergent results in the literature. With national standardization of all parameters, the widely divergent results seen in the literature should narrow, and regional medians will no longer be necessary.

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

OBJECTIVE: Historically, alpha-fetoprotein (AFP) levels in insulin-dependent diabetes (IDDM) have shown an approximately 20% decrement, and a correction factor is used to standardize multiples of the median (MOMs). With new laboratory methods and improved precision, we sought to re-evaluate the correctness of this approach. STUDY DESIGN: Consecutive biochemical screens were conducted among 60,287 nondiabetic patients and 307 patients with IDDM. Analyses were conducted in one laboratory, and comparisons were made with use of standard formula weight adjustments including a 20% correction factor for IDDM. Patients were then stratified according to maternal weight. RESULTS: Nondiabetic patients averaged 1.00 MOM, IDDM patients 0.91 MOM with no adjustments, 0.96 MOM adjusting for weight only, and 1.20 MOM adjusting for weight and diabetes status. To explain the "overcorrection," analysis by maternal weight showed significant overrepresentation of IDDM patients at 175 pounds or above. In fact, the mean weight in pounds for nondiabetic subjects was 151 +/- 35 and for those with IDDM 174 +/- 52 (P <.001). With use of an upper limit weight cutoff of 200 pounds, results are within 4% of normal. CONCLUSIONS: With current methodologies, the 20% correction factor for IDDM erroneously overcorrects. Two hundred pounds is sufficient, the weight correction for diabetic status should be abandoned.