Testosterone Deficiency

Testosterone deficiency, also known as hypogonadism, occurs when the body produces insufficient amounts of testosterone, the primary male sex hormone. This condition affects both physical and psychological aspects of health in men, including sexual function, muscle mass, bone density, mood, and energy levels. The likelihood of testosterone deficiency increases with age, though many cases may go undiagnosed.

Dr Ben Ng

Senior Consultant Endocrinologist

Dr Donovan Tay

Senior Consultant Endocrinologist

Symptoms of Testosterone Deficiency

Men with testosterone deficiency may experience a range of symptoms that vary in severity. Common symptoms include:

Sexual Dysfunction

Low testosterone commonly causes reduced libido and erectile dysfunction. Men may notice a decrease in spontaneous erections and overall sexual satisfaction.

Fatigue

Persistent tiredness and decreased energy levels occur despite adequate sleep. This fatigue may limit daily activities and exercise capacity.

Reduced Muscle Mass

Declining testosterone leads to decreased muscle mass and strength. This occurs gradually and may be noticed as difficulty maintaining muscle despite exercise.

Increased Body Fat

Testosterone deficiency alters body composition, leading to increased body fat, particularly around the abdomen. This may also contribute to gynaecomastia (enlarged breast tissue).

Mood Changes

Many men experience low mood, irritability, and difficulty concentrating. The hormonal imbalance affects neurotransmitters that regulate mood and cognitive function.

Decreased Bone Density

Over time, low testosterone reduces bone mineral density, increasing fracture risk. This effect may not produce noticeable symptoms until a fracture occurs.

Hair Loss

Reduced body and facial hair growth may occur. The pattern differs from male pattern baldness and affects overall hair distribution.

Gynaecomastia

Testosterone deficiency can cause enlarged breast tissue in men due to a hormonal imbalance between testosterone and estrogen levels.

Causes and Risk Factors

Testosterone deficiency develops due to various factors that interfere with hormone production or function throughout the body.

Ageing

Testosterone levels gradually decline after 40 as part of the natural ageing process, though the extent varies between individuals.
Primary Hypogonadism

Testicular failure leads to reduced testosterone production. This can result from injuries, infections, chemotherapy, radiation, or genetic conditions.
Secondary Hypogonadism

Dysfunction of the hypothalamus or pituitary gland disrupts signals that stimulate testosterone production. This may stem from pituitary tumours, medications, or systemic diseases.
Chronic Health Conditions

Diabetes, obesity, kidney disease, liver disease, and HIV/AIDS can reduce testosterone levels. These conditions alter hormone metabolism and production pathways.
Medications

Certain drugs, particularly those used to treat prostate cancers like androgen deprivation therapy, or certain blood pressure medications like spironolactone and some psychiatric medications, suppress testosterone. The effect is often dose-dependent and may resolve after discontinuation.
Lifestyle Factors

Poor diet, lack of exercise, excessive alcohol consumption, and chronic stress contribute to lower testosterone. These factors affect multiple hormonal systems in the body.

Diagnostic Methods

Medical History and Physical Examination

A detailed assessment of symptoms, medical conditions, medications, and lifestyle factors provides initial clues to testosterone deficiency. The physical examination includes evaluating body hair distribution, muscle mass, testicular size, and signs of hormonal imbalances, guiding further testing.

Blood Hormone Testing

Multiple morning blood samples measure total testosterone, as levels fluctuate throughout the day and peak in the morning. A diagnosis typically requires at least two low measurements. Additional tests may assess free testosterone, which represents the biologically active form.

Pituitary Function Tests

Measuring luteinising hormone (LH) and follicle-stimulating hormone (FSH) helps determine whether the deficiency originates in the testes (primary hypogonadism) or the brain (secondary hypogonadism). Elevated LH and FSH suggest a testicular cause, while low or normal levels indicate a central cause.

Additional Blood Tests

Evaluating prolactin, complete blood count, liver and kidney function, and blood glucose levels can help identify underlying conditions that may contribute to testosterone deficiency.

Imaging Studies

MRI of the pituitary gland may be recommended if secondary hypogonadism is suspected, while testicular ultrasound can help detect structural abnormalities affecting hormone production.

Treatment Options

Management of testosterone deficiency focuses on restoring hormone levels, alleviating symptoms, and addressing underlying causes when possible. Treatment approaches depend on the cause, severity, and patient considerations.

Testosterone Replacement Therapy (TRT)

Testosterone is administered through injections, gels, or patches. Injections are given at intervals of 2–10 weeks, while gels and patches require daily application to provide stable hormone levels. TRT aims to maintain testosterone within the mid-normal range while minimising side effects.

Clomiphene Citrate

This oral medication stimulates the body’s natural testosterone production by blocking oestrogen receptors in the hypothalamus, increasing signals to produce testosterone. It is particularly suitable for younger men who wish to preserve fertility, as TRT can suppress sperm production.

Human Chorionic Gonadotropin (hCG)

This injectable treatment mimics luteinising hormone (LH), stimulating the testes to produce testosterone. It is used several times weekly and helps maintain testicular size and fertility while raising testosterone levels.

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Prevention and Management

Maintaining healthy testosterone levels involves regular monitoring, lifestyle optimisation, and medical management when needed. A balanced diet rich in zinc, vitamin D, and healthy fats supports hormone production, while resistance exercise and adequate sleep promote optimal levels. Managing stress helps prevent cortisol from suppressing testosterone.

Men on testosterone therapy require regular blood tests to monitor hormone levels, haematocrit, prostate health, and cholesterol. Discussing treatment expectations with partners can help navigate potential changes. For those wishing to preserve fertility, sperm banking before long-term testosterone therapy may be considered.

Frequently Asked Questions

How long does it take for testosterone replacement therapy to show results?

The timeline for improvement varies. Most men notice increased energy and improved mood within a few weeks. Changes in muscle mass, strength, and libido typically become more noticeable after a few months of consistent treatment.

What happens if testosterone deficiency is left untreated?

If left untreated, testosterone deficiency can lead to persistent fatigue, reduced muscle mass, increased body fat, mood disturbances, and a higher risk of osteoporosis and metabolic disorders such as type 2 diabetes. Long-term deficiency may also impact cardiovascular health.

What are the risks of stopping testosterone therapy suddenly?

Abruptly stopping testosterone therapy can lead to withdrawal symptoms, including fatigue, mood swings, irritability, decreased libido, and potential loss of muscle mass. It is generally recommended to taper off under medical supervision to allow the body to adjust gradually.

Dr Ben Ng

Senior Consultant Endocrinologist

As a senior consultant endocrinologist with over 20 years of clinical experience, Dr Ben Ng provides comprehensive care for patients managing various endocrine conditions. His expertise includes the diagnosis and treatment of diabetes, thyroid disorders, obesity, and a range of other metabolic and endocrine conditions.

Adj Asst Professor Dr Ben Ng Jen Min graduated from the Queens University of Belfast Northern Ireland, United Kingdom (UK).
He completed his postgraduate training with the certificate of completion of training (CCT) from the Royal College of Physicians (UK) with dual accreditation in diabetes and endocrinology and in general internal medicine.
In 2010, he was awarded an MD with honours by the University of Hull, UK, in recognition for his research in diabetes mellitus

Dr Donovan Tay

Senior Consultant Endocrinologist

As a senior consultant endocrinologist with over 20 years of clinical experience, Dr. Donovan Tay provides comprehensive care for patients managing various endocrine conditions. His expertise includes the diagnosis and treatment of diabetes, thyroid disorders, osteoporosis, and a range of other metabolic and endocrine conditions.

Dr. Donovan Tay graduated from the National University of Singapore (NUS) and obtained his membership in the Royal College of Physicians (UK), Master of Medicine (NUS), and Master of Clinical Investigation (NUS).
After completing training in endocrinology, he was conferred as a Fellow of the Academy of Medicine, Singapore (FAMS).
He further specialised in endocrinology with a fellowship at the prestigious Columbia University Medical Centre in New York City.

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