Maternal serum alpha-fetoprotein and altitude.
Maternal serum alpha-fetoprotein (MS-alphaFP) testing is widely used to screen for fetal defects. MS-alphaFP concentrations are affected by a number of variables such as gestational age, maternal weight, number of fetuses, race, and insulin-dependent diabetes. Undefined geographic factors may also influence MS-alphaFP. We have examined the effect of altitude in a sample of 1063 MS-alphaFP results selected to span a range of altitudes. The study sample was subjected to linear regression with and without a term for altitude, and multiple-of-the-median (MoM) values were calculated before and after adjusting for altitude. The median MS-alphaFP was found to decrease an average of 1 ng/mL for every 1100 ft increase in altitude, a change approximately equivalent to that seen with an increase in maternal weight of 6 lb. Adjusting for altitude resulted in the reclassification of 36 of 1063 patient results (3.4%), although the clinical utility of this adjustment remains unexamined.
Nuttall
K L
KL
Department of Pathology, University of Utah, Salt Lake City, UT, USA. nuttall@arup-lab.com
Lenke
R R
RR
Ashwood
E R
ER
D000531:Altitude; D005260:Female; D006801:Humans; D011247:Pregnancy / Q000097:blood*; D000509:alpha-Fetoproteins / Q000378:metabolism*
D000509:alpha-Fetoproteins