Blood Kidneys

Erythropoietin (EPO)

Written by the VitaWhat editorial team · Medically reviewed by Steve Davis · Last reviewed 19 July 2026 · Editorial policy

Signals the bone marrow to make red blood cells.

What it does

  • Stimulates production of red blood cells in response to low oxygen

Too much

  • Too much (e.g. doping or a tumour) thickens the blood and raises clot risk

Too little

  • Low EPO in kidney disease causes anaemia
Keeping it balanced: Healthy kidneys and iron stores support red-cell production.

Sources & references

  1. You and Your Hormones (Society for Endocrinology)
  2. NHS — Hormonal conditions

Think a hormone may be out of balance?

The symptoms of hormonal excess and deficiency are non-specific — tiredness, weight change, low mood and poor sleep have many everyday causes. No hormone problem can be self-diagnosed from a symptom list.

Diagnosis needs blood tests interpreted alongside your history, sometimes repeated at set times of day because many hormones vary hour to hour. Speak to a GP if symptoms are persistent; seek urgent care for severe symptoms such as confusion, fainting, chest pain or extreme thirst with frequent urination.

Related entries

Adrenaline (Epinephrine)AldosteroneCalcitoninCortisolDopamineFollicle-Stimulating Hormone (FSH)
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