Testosterone, the primary male sex hormone, does have a physiological role in stimulating red blood cell production, but it is not a standard treatment for most types of anaemia in the UK. Whilst testosterone can increase haemoglobin levels through its effects on erythropoietin and bone marrow, its use for anaemia is limited to highly specific clinical scenarios such as certain bone marrow failure syndromes or anaemia associated with confirmed male hypogonadism. The vast majority of anaemia cases are treated with nutritional supplementation, erythropoiesis-stimulating agents, or management of underlying conditions. This article examines when testosterone might be considered, the mechanisms involved, and the more common NHS treatment approaches for anaemia.

Understanding Anaemia and Its Causes

Anaemia is a condition characterised by a reduction in the number of red blood cells or the amount of haemoglobin within them, leading to decreased oxygen-carrying capacity in the blood. This can result in symptoms such as fatigue, weakness, shortness of breath, dizziness, and pale skin. According to the World Health Organization, anaemia is defined as haemoglobin <130 g/L in men and <120 g/L in non-pregnant women, though laboratory reference ranges may vary.

The causes of anaemia are diverse and can be broadly categorised into three main mechanisms:

• Decreased red blood cell production – This may result from nutritional deficiencies (iron, vitamin B12, folate), bone marrow disorders, chronic kidney disease, or chronic inflammatory conditions

• Increased red blood cell destruction (haemolysis) – Conditions such as sickle cell disease, thalassaemia, or autoimmune haemolytic anaemia can lead to premature breakdown of red blood cells

• Blood loss – Acute or chronic bleeding from the gastrointestinal tract, heavy menstrual periods, or trauma can deplete red blood cell stores

Initial investigation of anaemia typically begins with a full blood count, red cell indices and ferritin. Additional tests such as blood film examination, reticulocyte count, or other specific investigations may be performed based on these initial results and the clinical context. Iron deficiency anaemia is the most common form, particularly among women of childbearing age and older adults. NICE guidance (NG12) recommends that men and postmenopausal women with confirmed iron deficiency anaemia should undergo gastrointestinal investigation, with urgent referral for those aged 60 and over.

Identifying the underlying cause is essential, as treatment must address the root problem rather than simply the low haemoglobin level. In some specific circumstances, hormonal factors—including testosterone—may play a role in red blood cell production, though this represents a relatively uncommon treatment approach in mainstream NHS practice.

How Testosterone Affects Red Blood Cell Production

Testosterone, the primary male sex hormone (androgen), has a well-established physiological role in stimulating erythropoiesis—the process of red blood cell production in the bone marrow. This effect occurs through several mechanisms that work in concert to enhance the body's oxygen-carrying capacity.

The primary mechanism involves testosterone's effect on erythropoietin (EPO) levels. Erythropoietin is a hormone that signals the bone marrow to increase red blood cell production. Testosterone appears to increase EPO levels, creating a more robust erythropoietic response. Additionally, testosterone may influence bone marrow stem cells, promoting their differentiation into red blood cell precursors.

Testosterone also influences iron metabolism, which is crucial for haemoglobin synthesis. It can affect the expression of hepcidin, a hormone that regulates iron absorption and distribution in the body. By modulating iron availability, testosterone indirectly supports the production of functional red blood cells.

This physiological relationship explains why men typically have higher haemoglobin levels compared to women. It also accounts for why individuals with hypogonadism (testosterone deficiency) may develop a mild normocytic, normochromic anaemia as part of their clinical presentation.

However, it is important to note that whilst testosterone does stimulate red blood cell production, this does not mean it is a standard or first-line treatment for most types of anaemia. In the UK, testosterone is licensed only for the treatment of confirmed male hypogonadism, with any improvement in haemoglobin being a secondary effect rather than a primary indication. The erythropoietic effect of testosterone is most clinically relevant in specific contexts, such as certain bone marrow failure syndromes or anaemia associated with male hypogonadism, rather than common nutritional or chronic disease-related anaemias.

Who Might Be Considered for Testosterone Therapy

Testosterone therapy for anaemia is not a routine treatment on the NHS and is reserved for highly specific clinical scenarios. The decision to use testosterone must be made by a specialist, typically a haematologist or endocrinologist, following comprehensive investigation and consideration of alternative treatments.

Conditions where testosterone therapy may be considered include:

• Aplastic anaemia and bone marrow failure syndromes – In some cases of aplastic anaemia (where the bone marrow fails to produce adequate blood cells), androgens may be used as part of specialist treatment protocols. This is rare, specialist-only, and often involves androgens other than testosterone (such as oxymetholone or danazol). This approach is typically considered for patients who are not candidates for bone marrow transplantation or who have not responded to immunosuppressive therapy

• Myelodysplastic syndromes (MDS) – Certain low-risk MDS patients may benefit from androgen therapy in specialist settings, though this is uncommon in routine UK practice

• Anaemia associated with male hypogonadism – Men with confirmed testosterone deficiency (hypogonadism) who also have anaemia may see improvement in their haemoglobin levels with testosterone replacement therapy. Diagnosis requires morning testosterone measurements on at least two occasions, along with LH/FSH levels and assessment of symptoms. The primary indication for treatment would be the hypogonadism itself, with anaemia improvement being a secondary benefit

It is important to note that testosterone has no recommended role in the treatment of anaemia related to chronic kidney disease, where erythropoiesis-stimulating agents (ESAs) are the standard approach per NICE guidance (NG8).

Before considering testosterone therapy, patients must undergo thorough investigation. Bone marrow examination would only be required for suspected marrow failure syndromes, not for hypogonadism-related anaemia. Testosterone therapy is contraindicated in individuals with known or suspected prostate cancer, male breast cancer, and should not be initiated or continued if haematocrit exceeds 54%. Caution is required in patients with cardiovascular disease or heart failure. The MHRA emphasises careful patient selection and monitoring due to potential risks associated with testosterone use.

Risks and Side Effects of Testosterone Treatment

Testosterone therapy carries potential risks and side effects that must be carefully weighed against any anticipated benefits. The MHRA and EMA have reviewed the safety of testosterone products and recommend they should only be used for confirmed male hypogonadism with appropriate monitoring.

Common side effects include:

• Polycythaemia (excessive red blood cell production) – Ironically, whilst testosterone's erythropoietic effect may benefit some anaemic patients, it can lead to elevated haemoglobin and haematocrit levels, potentially increasing the risk of blood clots. If haematocrit exceeds 54%, testosterone therapy should be interrupted, the dose reduced, or venesection considered until levels normalise

• Cardiovascular considerations – The MHRA and EMA have noted that evidence regarding cardiovascular risk is inconclusive and inconsistent. However, caution is advised in men with pre-existing cardiovascular disease, and appropriate monitoring is recommended

• Prostate effects – Testosterone can stimulate prostate growth, potentially worsening benign prostatic hyperplasia (BPH) symptoms. Regular prostate-specific antigen (PSA) monitoring and digital rectal examination are required

• Mood and behavioural changes – Some individuals experience mood swings, irritability, or aggressive behaviour

• Fluid retention and oedema – This requires caution in patients with heart failure or hypertension

• Sleep apnoea – Testosterone may worsen obstructive sleep apnoea

• Skin reactions – Acne, oily skin, and injection site reactions (with intramuscular preparations) are common

• Suppression of natural testosterone production – Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis, potentially affecting fertility

Patients receiving testosterone therapy require regular monitoring including haemoglobin/haematocrit (every 3-6 months initially), serum testosterone, PSA levels, and prostate examination. Additional tests such as liver function or lipid profiles may be required depending on the preparation used and individual risk factors.

Patients should be advised to seek immediate medical attention if they experience chest pain, shortness of breath, leg swelling, or sudden neurological symptoms. Any suspected adverse reactions should be reported via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

Alternative Treatments for Anaemia on the NHS

The NHS offers a range of evidence-based treatments for anaemia, with the specific approach depending on the underlying cause. These mainstream treatments are far more commonly used than testosterone therapy and should always be considered first-line options.

Nutritional supplementation forms the cornerstone of treatment for deficiency-related anaemias:

• Iron supplementation – Oral ferrous sulphate or ferrous fumarate is first-line for iron deficiency anaemia. Lower doses or alternate-day dosing may improve absorption and tolerance. Intravenous iron may be used when oral preparations are not tolerated or absorbed, or when rapid repletion is needed

• Vitamin B12 replacement – Intramuscular hydroxocobalamin injections are standard for B12 deficiency, typically given initially as a loading regimen followed by maintenance doses

• Folic acid supplementation – Oral folic acid 5mg daily treats folate deficiency anaemia

Erythropoiesis-stimulating agents (ESAs) such as epoetin alfa or darbepoetin alfa are used for anaemia of chronic kidney disease (per NICE NG8) and certain chemotherapy-related anaemias. These directly stimulate red blood cell production and are more targeted than testosterone therapy.

Treatment of underlying conditions is essential. This may include managing chronic inflammatory diseases, treating gastrointestinal bleeding sources, or addressing haemolysis. NICE guidance emphasises that investigation and treatment of the underlying cause should occur concurrently with symptomatic management. Men and postmenopausal women with confirmed iron deficiency anaemia should undergo gastrointestinal investigation, with urgent referral for those aged 60 and over (NICE NG12).

Blood transfusion remains an important acute intervention for severe symptomatic anaemia or when rapid correction is necessary. NICE guidance (NG24) recommends a restrictive transfusion strategy in most circumstances.

Specialist haematology treatments including immunosuppressive therapy, bone marrow transplantation, or disease-specific medications are available for complex anaemias such as aplastic anaemia, myelodysplastic syndromes, or haemolytic conditions.

Patients experiencing persistent fatigue, breathlessness, or other symptoms suggestive of anaemia should contact their GP for assessment. Early investigation with a full blood count can identify anaemia and guide appropriate, evidence-based treatment tailored to the underlying cause.

Frequently Asked Questions