Is a hemoglobin (Hb) level of 118 indicative of symptomatic anemia in an adult?

Is Hemoglobin 118 g/L (11.8 g/dL) Symptomatic?

A hemoglobin of 118 g/L (11.8 g/dL) meets the diagnostic threshold for anemia in both adult males and females, and while symptoms can occur at this level, many patients remain asymptomatic—symptom presence depends on the rate of decline, underlying cause, and individual physiological reserve. 1

Diagnostic Thresholds for Anemia

The diagnosis of anemia should be made at hemoglobin concentrations less than 135 g/L (13.5 g/dL) in adult males and less than 120 g/L (12.0 g/dL) in adult females. 1 Your hemoglobin of 118 g/L falls below the threshold for both sexes, confirming anemia by current guideline standards. 1

Important caveat: If you live at altitude ≥3,000 feet (914 meters), these thresholds must be adjusted upward by approximately 0.5-0.9 g/dL per 1000 meters of elevation to avoid underdiagnosis of anemia. 2 Failure to account for altitude leads to missing true anemia cases. 2

Symptom Development at This Hemoglobin Level

When Symptoms Typically Occur

• Gradual decline: Patients with slowly progressive anemia (as seen in chronic kidney disease) can maintain hemoglobin levels around 11.8 g/dL and remain relatively stable without immediate symptoms, particularly if the decline has been gradual. 1

• Acute decline: If hemoglobin dropped rapidly to 118 g/L, symptoms are much more likely due to inadequate physiological compensation time. 3

• Symptom spectrum: When present, symptoms include weakness, fatigue, shortness of breath, and decreased exercise tolerance related to reduced oxygen-carrying capacity. 3

Individual Variation in Symptom Threshold

• Older adults (≥60 years) may experience symptoms at higher hemoglobin levels due to reduced physiological reserve and comorbidities. 4, 3

• Iron deficiency can cause symptoms even before hemoglobin drops below 120 g/L, meaning you could be symptomatic from iron deficiency itself rather than the anemia severity. 5

• Patients with cardiovascular or pulmonary disease develop symptoms at higher hemoglobin levels than healthy individuals. 3

Mandatory Next Steps Regardless of Symptoms

You must investigate the cause of anemia at this hemoglobin level, even if asymptomatic. 5, 3

Immediate Laboratory Evaluation

• Check complete iron studies immediately: ferritin, transferrin saturation, serum iron, and total iron-binding capacity (TIBC). 5

• Assess mean corpuscular volume (MCV) to categorize as microcytic, normocytic, or macrocytic. 3

• If iron parameters are abnormal, proceed with full investigation for the source of iron loss. 5

Common Causes to Evaluate

• Nutritional deficiency (iron, folate, vitamin B12) accounts for approximately one-third of cases. 4

• Chronic disease/inflammation (chronic kidney disease, inflammatory conditions) accounts for another third. 4, 3

• Occult blood loss: In females with confirmed iron deficiency, 60-70% will have a gastrointestinal source identified on endoscopy, even in premenopausal women. 5 Review NSAID use, which commonly causes occult GI bleeding. 5

• "Unexplained anemia" comprises the remaining third, potentially due to bone marrow resistance to erythropoietin and subclinical inflammation. 4

Special Consideration for Chronic Conditions

If you have chronic kidney disease, heart failure, or chronic liver disease, the relationship between hemoglobin concentration and total hemoglobin mass may be distorted by plasma volume expansion. 6 In these conditions, anemia may reflect plasma volume excess rather than true hemoglobin deficiency, potentially requiring different management approaches. 6

Clinical Significance and Risk

Low-normal hemoglobin levels (even 130-139 g/L in men, 110-119 g/L in women) and mild anemia are associated with more than doubled risk of end-stage renal disease, particularly in the presence of albuminuria or reduced kidney function. 7 This risk increases synergistically with lower estimated glomerular filtration rate. 7

Common Pitfalls to Avoid

• Don't assume asymptomatic means benign: Anemia at 118 g/L requires investigation regardless of symptom presence. 5, 3

• Don't forget altitude adjustment: Using unadjusted WHO criteria at altitude will miss true anemia cases. 2

• Don't skip iron studies in premenopausal women: The assumption that menstruation explains anemia misses significant GI pathology in 60-70% of cases. 5

• Don't rely solely on hemoglobin without assessing iron status: Iron deficiency can be masked by altitude-induced elevation or cause symptoms before meeting anemia thresholds. 2, 5