Getting Shorter with Age: What Should I Do?

Dr. LAM Wing Ching, Nicole

Resident Medical Officer

As we age, we fear losing our eyesight, hearing ability, cognition, or suffer from stroke, heart diseases and cancers. However, decreasing height can be as alarming as these conditions. Height loss can be caused by vertebral disc degeneration, vertebral fractures, sarcopenia and change in posture. It is known to occur from the fourth decade of life and accelerates from seventh decade onwards.

Osteoporosis is thought to be one of the main factors associated with height loss. The resultant height loss affects the normal functioning of our cardiopulmonary and gastrointestinal systems, which may cause malnutrition and further decrease in skeletal muscle mass. Studies showed that a height loss of more than 5 cm in older women was associated with a nearly 50% increase of risk of hip fracture and non-spinal fracture.

Elderly Beware: Low Bone Density and Low Muscle Mass

Low Bone Density: Osteoporosis – The Silent Thief

Osteoporosis is an age-related disease characterised by compromised bone density and bone quality, leading to increased risk of fractures. While most seniors may mistake bone pain as a symptom of osteoporosis, it is asymptomatic in most cases. 

In Hong Kong, almost one in four elderly women and men aged 65 and above has osteoporosis. Osteoporosis is initiated by an imbalance between bone resorption and formation. There is a number of risk factors for osteoporosis. Some risk factors are non-modifiable, e.g. sex, age and family history, while others could be altered. Certain endocrine disorders, gastrointestinal disorders, medications (e.g. oral glucocorticoids) and rheumatoid arthritis can cause secondary osteoporosis. In particular, diabetic bone disease (DBD) is emerging as a serious but previously neglected chronic complication of diabetes. Fracture risk is thus encouraged to be assessed in older adults with diabetes as part of routine care.

Noticeably, osteoporosis-related vertebral fractures contributing to height loss and kyphosis occur slowly over time. They are thus often left undiagnosed. Studies reveal that detecting height loss is an effective tool to identify patients with vertebral fractures, as well as low bone mineral density and vitamin D deficiency. Clinical guideline recommends yearly height measurements in post-menopausal women and men older than 50. Vertebral imaging is also recommended when the height loss from peak height exceeds 4 cm or recent height loss exceeds 2 cm.

Assessment, Diagnosis and Treatment

One of the commonly used fracture risk assessment tools is the Fracture Risk Assessment (FRAX) model¹. It is a simple ethnic-specific web-based tool that integrates clinical information to predict the 10-year probability of major osteoporotic fracture and hip fracture for both post-menopausal women and men aged 50 or above.

In 2024, a Chinese osteoporosis screening algorithm (COSA) was introduced by HKU as an osteoporosis risk prediction tool developed specifically for the Chinese population. Using a patient’s sex, age, weight, and history of non-traumatic fracture, COSA can accurately determine an individual’s risk of osteoporosis as either high or low. High-risk individuals may undergo a Dual-energy X-ray absorptiometry (DXA) bone density examination for further assessment.

DXA is currently regarded as the gold standard for diagnosis of osteoporosis. It could also be used for assessment of fracture risk and monitoring of changes in BMD overtime.

The World Health Organization has defined osteoporosis and osteopenia on the basis of T-scores derived from bone mineral density (BMD) measurements at the lumbar spine or proximal femur, i.e. normal BMD: T-score ≥ –1.0, osteopenia or low bone mass: -2.5 < T-score < –1.0, or osteoporosis: T-score ≤ –2.5.

If a post-menopausal woman or elderly man has sustained a low-energy fracture, i.e. a fracture that occurs from a fall from standing height or less, a clinical diagnosis of osteoporosis can be established.

The Osteoporosis Society of Hong Kong recommends universal DXA screening for all men aged 70 years or above and women aged 65 years or above. Screening at a younger age should be considered if additional risk factors for osteoporosis are present.

The ultimate goal of pharmacological treatment is to reduce fracture risk, increase survival, and improve quality of life. Depending on individual’s health status, doctors will prescribe medications for osteoporosis, such as hormone replacement therapy, bisphosphonates, raloxifene, teriparatide or denosumab. They will also monitor efficacy of treatment on patients as well as side effects of medications, and arrange subsequent BMD monitoring.

Low Muscle Mass: Sarcopenia

Sarcopenia is defined as low skeletal muscle mass, muscle strength and physical performance. Apart from height loss, sаrϲοpеnia is associated with increased rates of functional impairment, disability, falls and mortality. As muscle tissue is increasingly recognised as a major contributor to whole-body insulin sensitivity, sаrϲοpeոia is therefore also associated with insulin resistance, type 2 ԁiabetes, and the metabolic syndrome, with the attendant increased risks of cardiovascular disease and strοkе.

In Hong Kong, the prevalence of sarcopenia is reported to be 9% among community-dwelling Chinese adults aged 65 years or above. Age-related decline of muscle quantity and quality is referred to as primary sarcopenia. Up to 40% of muscle mass may be lost between the age of 20 and 70 years and a decline of muscle mass at 1.4%–2.5% per year after 60 has been noted. Secondary causes of sarcopenia include low physical activity, smoking, malnutrition, low serum vitamin D levels, certain endocrine diseases, gut microbiota dysbiosis, neuromuscular disease, organ failure, cancer, and inflammatory conditions.

Assessment, Diagnosis and Treatment

The SARC-F questionnaire² is a self-assessment tool that screens patients for signs suggestive of sarcopenia. Data suggests that a SARC-F score of ≥4 best predicts the risk of having sarcopenia and the need for further evaluation.

Sarcopenia is confirmed by data obtained from dual-energy X-ray absorptiometry or bioimpedance analysis, together with handgrip strength and physical performance score.

Management of sarcopenia typically involves resistance training coupled with nutrition supplementation, particularly protein. Other nutrients that are potentially beneficial for sarcopenia include leucine, β-hydroxy β-methylbutyrate, omega-3 fatty acid and other antioxidants.

As the peaks of both muscle volume and strength are reached in the third and fourth decades of life, an effort to primarily prevent sarcopenia needs to be initiated in 20s. Maintaining the peak during adulthood and minimising the loss in old age by leading a healthier lifestyle can keep our skeletal muscle strong for a longer period.

Prevent Low Bone Density and Low Muscle Mass

Patients with osteosarcopenia have a higher chance of falls and fractures than those with either osteoporosis or sarcopenia alone. Want to stay young and healthy? Start eating well and adopt healthy lifestyles. 

1. Adequate Intake of Calcium
   • Eat a calcium-rich diet to maintain bone density.
     • Dairy products, e.g. yogurt, milk, cheese
     • Seafood with bones, e.g. sardine
     • Soya bean products, e.g. tofu, fortified soy milk, beancurd stick and beancurd sheet
     • Dark green leafy vegetables, e.g. white cabbage, broccoli and Choy-sum
     • Nuts, e.g. almond and sesame
   • Consider calcium supplementation of 1000-1200 mg daily for patients who cannot obtain sufficient calcium from food, especially those with lactose intolerance.
   • The total amount of calcium intake should not exceed 2000 mg daily to avoid harmful effects, notably renal stones.
2. Adequate Intake of Vitamin D
   • Vitamin D, which helps the body to absorb calcium, has been shown to significantly reduce fall risk.
   • While it is relatively scarce in food, main dietary sources of vitamin D are saltwater fish (i.e. salmon, tuna, and mackerel), egg yolks, and vitamin D-fortified milk or cereal products.
   • A vitamin D intake of 800-1000 IU daily is recommended.
   • Engage in outdoor activities to absorb sunlight. It helps the body to produce more vitamin D.
3. Adequate Intake of Protein
   • Adequate dietary protein intake is essential for optimal growth and maintenance of the structure and function of our musculoskeletal system.
   • A dietary protein intake of 1.0-1.2 g/kg body weight per day is recommended with at least 20-25 g of high-quality protein at each main meal.
4. Adequate Exercise
   • Exercise plays an important role in achieving peak bone mass as well as maintaining bone strength. Substantial evidence showed that resistance training 2–3 times per week can improve muscle strength and physical function in older people, and these beneficial effects have been shown to have sustained effect. Regular weight-bearing, muscle-strengthening and balance training exercises not only have favourable effects on BMD but also are particularly useful to improve agility, strength, posture, coordination and balance.
   • Brisk walking, Tai Chi, dancing are some of the recommended low impact weight-bearing exercises for elderly people, especially if they have concomitant osteoarthritis.
   • Maintain a good posture and avoid stooping. Weak back and abdominal muscles contribute to poor posture. Simple plank pose can strengthen these muscles and help you stand taller.
5. Avoid smoking, as smoking cigarettes is known to speed up bone loss and muscle loss.

1. shef.ac.uk/FRAX/
2. jococ.org/zh-hk/FRAX-SARC-F.php