Q:We hear an awful lot about hypertension high blood pressure but not so much about hypotension low blood pressure. My wife is suffering from all the usual attendant symptoms: lack of energy, tires quickly, sleeps more than most (10-11 hours a night)

A:Some doctors will tell you that hypotension is a blessing and not a disease. When a patient presents with the collection of symptoms you mention, the tendency is either to call them hypoglycemic (suffering from low blood sugar) or hypotensive. If you do not have a history of heart problems and you are not taking drugs which can affect your blood pressure, and if you are not pregnant or diabetic, then finding the cause of low blood pressure can be difficult. So called neurally mediated hypotension (NMH) occurs after prolonged periods of standing. There is fatigue after modest exertion which can last 24 to 72 hours, and interferes with daily activities, as well as recurrent light headedness and fainting.

With NMH, the body has trouble regulating blood pressure, particularly when upright. There seems to be a misconnection between the brain and the nerves that control the blood pressure and heart rate. The reasons are not clear, but recent research at Johns Hopkins University in Baltimore, links NMH with other disorders such as chronic fatigue syndrome (CFS) and fibromyalgia syndrome (FMS) (JAMA, 1995; 274: 961-7). It is thought that post viral damage to the autonomic (involuntary) nervous system is a possible cause.

One way to diagnose NMH is with something called the tilt table test (TTT), where you lie strapped to a examination table which is slowly tilted to an upright position. Blood pressure and pulse rate are monitored, and a fall in blood pressure along with a sudden drop in pulse rate indicates a positive result. If your blood pressure does not fall during this phase of the test, you will be injected with a drug to raise the pulse rate.

If your blood pressure and pulse rate fall during this stage of the test, this is also considered a positive result.

Research on the TTT is thin on the ground. Many people faint during the test and some report that the medication makes them feel as if their hearts are about to burst open. Rather than subject an individual to this strenuous experience some doctors feel it is better to simply take a careful patient history.

Once diagnosed, there is no universal treatment for NMH. Simply advising more salt may be unhelpful and, for some, dangerous. There is no medication to cure hypotension, only to control symptoms, and what there is can cause distressing side effects.

One drug that has recently been approved for use is midodrine (ProAmatine). This drug needs to be prescribed with care since it can cause a marked elevation in supine (lying down) blood pressure (up to 200 mm Hg systolic). It should only be tried by those individuals whose lives are severely affected by hypotension and never on a just in case basis.

Another drug, Florinef (fludrocortisone) acts on the kidney to retain sodium, but it does so at the expense of losing more potassium into the urine. You will need to be on a high potassium diet while taking this drug. Side effects include headache, worsening of CFS, abdominal pain and depression.

Beta blockers such as Tenormin (atenolol) can also worsen CFS symptoms and existing asthma, cause depression and are also contraindicated in diabetics. Antiarrhythmics like Norpace (disopyramide) can also worsen CFS symptoms or existing glaucoma, as well as cause dry mouth, constipation or blurred vision.

Some find that even when on medication hypotension resurfaces or worsens when they are under stress.

Self help measures include, where practical, avoiding circumstances which might bring on symptoms, such as hot showers or standing too long. If you wish to increase your salt intake, but do not want to change the taste of your food, you can buy salt tablets.

Increasing your fluid intake, to at least two litres a day, is very important. Taking additional B12 may also assist in regulating blood pressure and nervous system response. Other supplements which help maintain a healthy nervous system include kelp, rich in B vitamins, carotene, potassium, iodine sodium, calcium, phosphorus and iron.

The herb broom (Sarothamnus scoparius) can help raise blood pressure. It can be used alone or in combination with hawthorn berries (Crataegus oxyacanthoides) to improve heart function.