Table 2.

Proposed adjustments^a to hemoglobin (g/L) by 500-m increments of altitude by population group

Altitude (m)	WHO cutoffsb	MMWR 1989 equationc	PSCd	WRAe
−50 to −1	0	0	0	0
0	0	0	0	0
1–499	0	0	1	1
500–999	0	1	4	4
1000–1499	2	2	7	7
1500–1999	5	5	10	10
2000–2499	8	10	13	13
2500–2999	13	15	16	17
3000–3499	19	22	20	20
3500–3999	27	29	24	24
4000–4499	35	38	28	28

^aAdjustment is amount (g/L) added to the hemoglobin cutoff defining anemia, or subtracted from an individual’s observed hemoglobin level.

^bWHO cutoffs published as the lowest altitude value in range (e.g., 1500 m for the 1500−1999 range).²

^cMMWR cutoffs calculated using Hb_adjustment (g/L) = [(−0.032 × (altitude × 0.0032808) + 0.022 × (altitude × 0.0032808)²) × 10], where altitude is based on the midpoint of altitude range (e.g., 1750 m for the 1500−1999 range).^8,10

^dProposed cutoffs calculated using Hb_adjust_altitude (g/L) = (0.0048108 × altitude) + (0.0000004 × altitude²), where altitude is based on the midpoint of altitude range (e.g., 250 m for the 1−499 range).

^eProposed cutoffs calculated using Hb_adjust_altitude (g/L) = (0.0052792 × altitude) + (0.0000003 × altitude²), where altitude is based on the midpoint of altitude range (e.g., 250 m for the 1−499 range).

Note: Current WHO recommendations and adjustments based on the MMWR 1989 equation provided for comparison.

PSC, preschool-aged children (6−59 months); WRA, women of reproductive age (15−49 years).