Metabolic bone disease

All through life bone is being cleared away and rebuilt, and that work needs a steady flow of calcium, phosphate and vitamin D, guided by several hormones. When metabolic bone disease upsets the flow, or the hormones that guide it, bone is built badly, poorly hardened with minerals or not kept in good repair, although nothing has inflamed it or worn it down.

Each condition has causes of its own. Among the commonest are too little vitamin D and a parathyroid gland working too hard or too little; others include a fault in the way the body handles calcium or phosphate, an overactive thyroid, kidney disease, and certain medicines, especially steroids taken for long periods.

Age, the menopause, too little time in the sun, a limited diet, and other illnesses or their treatment all make these problems likelier, and more than one can be at work.

The term covers a family of related problems, including:

• Osteoporosis, where bone loses strength until it breaks easily
• Softening of the bones (osteomalacia), often from too little vitamin D, which can bring aching bones and weak muscles
• Disorders of calcium and phosphate, such as an overactive or underactive parathyroid gland
• Damage to bone caused by a different illness, or by the medicine used for it

Your history and risk factors are brought together with blood and urine tests of minerals, vitamins and the chemistry of bone, and with scans where they add something. A DEXA bone density scan measures your bone density, the method used in current practice to gauge bone strength, while specialised tests of bone turnover can track the pace at which bone is renewed and, once treatment starts, how the bone is responding. The goal throughout is to find what is driving the problem, since a result read on its own can mislead.

Treatment goes for the cause: making good a missing vitamin or mineral, managing any illness that is driving the problem, and protecting or building up the bone where that is needed, with changes to daily habits beside it. Osteomalacia, for example, is usually treated with vitamin D and calcium; a parathyroid gland made overactive by a growth on it with an operation, or with a medicine that lowers the calcium where an operation is not wanted or not suitable, while a gland driven to overwork by low vitamin D or calcium can be treated by correcting them, with medicines and supplements; and an underactive one with calcium and vitamin D, usually for life. If an overactive parathyroid gland has raised your calcium, do not change your diet to try to bring it down unless your specialist advises it. Once the cause is known, these conditions can often be well controlled, and the plan is shaped around your own needs and revisited as things change. You and Dr Borukhson settle the plan together.

Progress with most of these conditions is measured in months, not days, and once the cause has been found and corrected the outlook is often good, which can ease the worry that comes with the diagnosis.

On top of what you have been prescribed, some habits do your bones direct good:

• Keep to the supplements you have been given, as you were told to take them, and turn up for blood tests and scans, so that the plan can follow your progress
• Put weight through your bones with walking or similar activity, and add gentle exercises for strength and balance, which also help to make a fall less likely
• On days when bone pain or tiredness is worse, ease off instead of forcing yourself on

If a medicine worries you, raise it with the team that prescribed it or your GP rather than simply stopping it; a new symptom is for the lists under When to seek help, which say how soon and where.

A slow change can be raised at a routine review. The signs below are set out in order of seriousness, each with its own route; in these conditions a calcium level that has fallen or risen a long way is behind several of them.

Treat any of these as a 999 or A&E emergency: call 999 and do not drive yourself to A&E.

• A fit, or confusion or drowsiness that comes on suddenly, or that is new when your calcium is known to be high or low, or a heartbeat that has become irregular when your calcium is known to be high, since a calcium level far out of range can cause them (a fit when it is low; drowsiness or an irregular heartbeat when it is high; confusion with either) and needs hospital treatment, though they can have other causes that are just as urgent
• Any difficulty breathing, a heartbeat that has become irregular, confusion, or muscles that lock in place (a hand or a foot stuck in a fixed position), with tingling, cramps, twitches or spasms, or when your calcium is known to be low, since in these conditions they can mean the calcium has fallen very low
• A joint you cannot put weight on or move, or that has moved out of place, or, after a fall or injury, very bad pain or any tingling or numbness
• After an injury, a crack heard as it happened, or skin around it that has turned blue, grey or cold, since these can be signs of a broken bone
• Numbness or tingling around the back passage, genitals or inner thighs, new difficulty passing urine or controlling your bladder or bowels, a change in feeling during sex, or pain, tingling, weakness or numbness in both legs, since these can mean pressure on the nerves at the base of the spine, which needs emergency treatment
• Back pain that began after a serious accident, such as a car crash or a fall from a height, or that comes with chest pain
• Chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away
• Lips, mouth, throat or tongue that suddenly swell, a throat that feels tight, very fast breathing or a struggle to breathe or to swallow, skin, tongue or lips turning blue, grey or pale (on black or brown skin this may be easier to see on the palms of the hands or the soles of the feet), becoming suddenly very confused, drowsy or dizzy, or fainting and not being able to be woken, since this can be a severe allergic reaction, anaphylaxis, which can follow a dose of any medicine

Any of these needs an assessment that is urgent, on the same day, from your GP or NHS 111:

• Tingling around the mouth or in the fingers or toes, or muscle cramps, twitches or spasms, a sign that your blood calcium may be too low (after recent neck surgery, the contact your surgical team gave you comes first); any difficulty breathing, a heartbeat that has become irregular, confusion, or muscles that lock in place with them is a 999 or A&E emergency, in the first list
• Being sick, or being so thirsty and passing so much urine that drinking cannot keep up, when your calcium is known to be high, since losing fluid can push the calcium higher still; confusion or drowsiness that is new belongs to the first list
• A bone, other than one in the spine, that may have broken in a minor fall or in everyday activity, which needs an X-ray the same day at an urgent treatment centre or A&E, with NHS 111 to tell you which; very bad pain, tingling or numbness after it, or a joint that takes no weight, will not move or is out of place, is in the first list, and a limb left at an odd angle or changed in shape is a 999 or A&E emergency too
• Severe back pain that came on suddenly, back pain that is fast getting worse, a change in the shape of your back that came on quickly, or new pain in the spine or the neck after lifting, coughing, a small strain or a knock, since a softened or thinned bone of the spine can break, and a break there should be looked for that day; pain after a serious accident is in the first list

Short of the signs in the lists above, thirst, passing more urine than usual, tiredness or constipation when your calcium is known to be high should go to your GP or the team that follows you within days. Bone or muscle pain that is slowly getting worse, new loss of height, repeated breaks, or blood tests about your bones that have come back abnormal are reasons for a routine review. Once you are under a team's care, how a treatment is suiting you is for that team to hear about, by phone or message, before your next appointment comes round. If you cannot tell how urgent something is, asking is never a mistake.

Getting to the cause is what makes effective, well-aimed treatment possible, because each of these conditions needs something different. If a bone blood test has come back abnormal, if bone pain has no clear explanation, or if you have other concerns about your bones, a specialist review can establish what is happening and what should be done about it.

How do doctors find out that I have it?

They start from your history and risk factors and add blood and urine tests: calcium, phosphate, vitamin D, the hormones that steer them, and markers of how bone is behaving. A DEXA scan gives your bone density, tests of bone turnover can reveal how fast bone is being renewed, and other scans are added when they would help. What is being looked for is the reason behind the results, not a single figure to correct, so that treatment can be chosen to suit you.

How are these conditions treated, and do the bones get better?

Treatment targets what has gone wrong: topping up vitamin D or a mineral that has run short, dealing with any illness behind the problem, and shoring up the bone where it needs it, together with changes to daily habits. Once the cause is found and dealt with, a good many of these conditions settle. Your progress is followed, with blood tests or scans repeated where useful, and the plan is altered as needed to keep your bones in the best health possible.

Is metabolic bone disease just another name for osteoporosis?

No. Osteoporosis belongs to the group, which is wider. It takes in osteomalacia, in which bones are softened, often by too little vitamin D, and the calcium and mineral disorders that harm bone. Each has its own causes and its own treatment, which is why careful assessment matters: once the exact condition is named, treatment can be aimed at it rather than given in the same way to everyone.

What can I do myself to help my bones?

A few steps usually help alongside any treatment you are given: eating a varied diet with enough calcium, getting enough vitamin D, keeping up exercise that puts weight through the bones and strengthens the muscles as far as you comfortably can, not smoking, and drinking in moderation. They support the bone, though they cannot stand in for correcting a cause. If you are unsure what suits you, it can be worked out with you during your assessment.

At what point should I ask a specialist to look at my bones?

A review is worth arranging if blood tests related to your bones have come back abnormal, if you have bone pain no one can account for, if a bone has broken unexpectedly, or if you are simply concerned about your bones. Bone strength depends on minerals, hormones and vitamins working in balance, and a specialist can find where that balance has slipped and agree a clear plan with you.