TABLE 3.

Availability and distribution of ferritin results and iron-deficiency status among pregnancies screened for anemia status in the first trimester, Kaiser Permanente Northwest, 2005–2016

	Among those with anemia,1 n = 1045		Among those without anemia,1 n = 37,878
Characteristic	n	% or median (IQR) [minimum-maximum]	n	% or median (IQR) [minimum-maximum]
Ferritin result available, %	197	18.9	1,275	3.4
TIBC result available, %	183	17.5	869	2.3
Serum iron result available, %	183	17.5	872	2.3
Ferritin, μg/L	197	15 (6–58) [1–2761]2	1,275	27 (15–47) [2–475]
TIBC, μg/L	183	379 (326–437)	869	346 (315–386)
		[213–646]		[111–579]
Serum iron, μg/L	183	53 (28–93) [10–184]	872	78 (54–106) [10–252]
ID among those with ferritin assessed (n = 1472)		n = 197		n = 1275
Ferritin <10 μg/L	79	40.1	140	11.0
Ferritin <15 μg/L	95	48.2	300	23.5
ID among those with TIBC assessed (n = 1052)		n = 183		n = 869
TIBC >400 μg/L	76	41.5	165	19.0
ID among those with serum iron assessed (n = 1055)		n = 183		n = 872
Serum iron <40 μg/L	67	36.6	91	10.4
ID among those with ferritin, TIBC, or serum iron assessed(n = 1656)		n = 231		n = 1425
Any iron test abnormal (ferritin, TIBC, or serum iron)	132	57.1	418	29.3
Ferritin <15 μg/L, if ferritin not available, then abnormal TIBC or serum iron (preferential to ferritin)	118	51.1	335	23.5

ID, iron deficiency; TIBC, total iron binding capacity.

¹Anemia defined as hemoglobin <11 g/dL (not adjusted for smoking or elevation) or hematocrit <33% based on first test result in the first 14 wk of gestation. Iron indicators based on first test result through 20 wk of gestation to ensure observation time for ordering and diagnostic testing of iron status.

²One ferritin result (>2000 μg/L) was a clear outlier. Review of record indicated patient diagnosed with genetic blood disorders and hemochromatosis with iron overload, and thus the value is considered biologically plausible and retained.