Hemoglobin 8 to 10.9 g/dL

WHO defines moderate anemia as 80 to 109 g/L (8.0 to 10.9 g/dL) for both men and non-pregnant women aged 15 to 65, the band between 60 and 80 percent of the cutoff under its 1989 severity rule. WHO's own remark on the table applies: management "could vary depending on the clinical scenario and the underlying cause(s)." What changes at this level is how quickly the cause is sought, not the list of causes.

Why urgency rises here. The BSG cites the UK's fast-track cancer referral thresholds, an iron deficiency anemia with hemoglobin under 110 g/L in men or under 100 in non-menstruating women, and says the case for investigation "is stronger in those with more severe degrees of anaemia, as they are more likely to have serious underlying GI pathology." Its background recommendation: "GI investigation on an urgent basis should be considered in adults with a new diagnosis of IDA without obvious explanation." Even in premenopausal women, whom the BSG otherwise spares endoscopy, it says there is sometimes justification for investigating younger women, particularly when the anemia is severe or recurrent and out of proportion to menstrual losses. Age, sex, hemoglobin and MCV are its four independent predictors of cancer risk.

The workup. Same panel as any anemia, read faster: ferritin (AGA's 45 ng/mL cutoff in patients with anemia), transferrin saturation and CRP when inflammation may hide iron deficiency, red cell indices, celiac serology, and a urine check for microscopic blood, because the BSG lists renal tract pathology as an uncommon but recognized cause. Men and postmenopausal women get gastroscopy and colonoscopy first line under both AGA and BSG. If both are negative, AGA suggests testing for H. pylori and a trial of iron before capsule endoscopy.

Treatment. BSG: do not defer iron "while awaiting investigations for IDA unless colonoscopy is imminent." Parenteral iron "should be considered when oral iron is contraindicated, ineffective or not tolerated," and at an early stage when "the correction of IDA is particularly urgent." The NHLBI says people "who have serious iron-deficiency anemia or who have long-term conditions are more likely to receive IV iron," and that oral iron "often takes three to six months to restore your iron levels." The response check is the same as for mild anemia: hemoglobin within 4 weeks, iron continued about 3 months after normalization, then periodic counts. The NHLBI's list of what untreated anemia can lead to is the reason not to wait: heart rhythm problems, an enlarged heart, heart failure, infections, pregnancy complications.