Reduced muscle mass

Reduced muscle mass means a loss of muscle bulk, often with reduced strength. Some decline is a normal part of ageing (sarcopenia), and muscle also shrinks with inactivity, bed rest or immobilisation of a limb. Beyond these, a more marked or unexplained loss can reflect a range of causes. Hormones are important builders of muscle: low testosterone in men (hypogonadism) reduces muscle and strength, growth hormone deficiency (as in hypopituitarism) reduces adult muscle mass and wellbeing, and an overactive thyroid speeds metabolism enough to break down muscle, causing weakness and weight loss. Muscle is also lost in chronic illnesses — such as heart, lung, kidney or liver disease, and cancer — and with poor nutrition or malabsorption, where the body lacks the protein and calories to maintain it. Some neurological and muscle diseases cause wasting too. So while much muscle loss is explained by age and activity, a significant or unexplained reduction — particularly with fatigue, weight loss or hormonal symptoms — is worth investigating for a treatable cause.

• Ageing (sarcopenia) — a natural, gradual loss of muscle.
• Inactivity, bed rest or immobilisation — muscle shrinks without use.
• Low testosterone (hypogonadism) — reduced muscle and strength in men.
• Growth hormone deficiency (hypopituitarism) — reduced adult muscle mass.
• Overactive thyroid — muscle breakdown with weight loss and weakness.
• Chronic illness — heart, lung, kidney, liver disease, or cancer.
• Poor nutrition or malabsorption — insufficient protein and calories.

When muscle loss is marked or unexplained, blood tests look for a treatable cause guided by the picture: testosterone (with LH and FSH) for low sex hormones, thyroid function (TSH and free T4) for an overactive thyroid, and IGF-1 if growth hormone deficiency or a pituitary cause is suspected. Tests of nutrition (protein, albumin), kidney and liver function, and inflammatory markers help assess chronic illness, and a full blood count screens broadly. Where a muscle disease is suspected, creatine kinase is checked. Mediora.AI can surface a low-testosterone, thyroid or IGF-1 pattern from your results that points toward a hormonal cause; the interpretation belongs with your doctor.