| Before we can look at postural hypotension we | | | | poisoning it is important to check your blood |
| must first review that basics of how blood | | | | pressure. |
| pressure works. | | | | Rare diseases of the nerves that control the |
| When you stand up, your blood immediately tries | | | | reflexes in the veins can prevent the veins from |
| to pool in the veins in your legs. If allowed to | | | | contracting when they stand up, resulting in a |
| occur, this would be a bad thing, because there | | | | severe drop in blood pressure. This is very rare. If |
| would be a shortage of blood in the rest of your | | | | you have a severe drop in blood pressure when |
| body. | | | | you stand and you are otherwise well, then you |
| This pooling of blood in the leg veins is stopped by | | | | should have further investigations. |
| nerves, which contract the leg veins ensuring that | | | | Diabetes can also cause damage to the nerves |
| enough blood returns to your heart and that | | | | supplying blood vessels and can therefore be |
| there is no reduction in the amount of blood that | | | | associated with a drop in pressure when standing |
| your heart pumps. This maintains the blood supply | | | | up. |
| to your brain and other parts of your body. | | | | Failure of the adrenal gland. The adrenal glands are |
| However, if there is pooling of blood in your veins, | | | | two very small glands just above the kidney that |
| less blood returns to your heart and less is | | | | produce important hormones, one of which is |
| pumped out which means a reduction in the | | | | aldosterone. This hormone is very important in |
| amount of blood going to your brain and other | | | | controlling the amount of salt in your body. |
| parts of your body. This causes symptoms of | | | | If your adrenal glands become damaged this can |
| dizziness and some people may faint as a result. | | | | mean that there is not enough aldosterone in your |
| Therefore, if you have a low blood pressure and | | | | body. This leads to a loss of salt from your body |
| you also have symptoms of dizziness or faintness | | | | and this may cause low blood pressure, with |
| when standing up suddenly you should have your | | | | dizziness or faintness when you stand up |
| blood pressure checked both when you are lying | | | | suddenly. This condition is very rare, but important |
| down and when you then stand up. This drop in | | | | to pick up as; it can easily be treated by replacing |
| blood pressure when you stand up is called | | | | the missing hormones. |
| postural hypotension. | | | | Investigations are only conducted if you have |
| One of most common causes of postural | | | | symptoms that suggest a fall in blood pressure |
| hypotension is the result of an acute illness, such | | | | when you stand up, such as dizziness or faintness. |
| as severe blood loss or sudden severe infection | | | | If you do have these symptoms then your |
| or damage to the heart may cause low blood | | | | doctor should conduct further tests or refer you |
| pressure and very low blood pressures when | | | | to a specialist. |
| sitting up or standing. When this happens blood | | | | This will mean having a tilt test where you will be |
| pressure levels are an important measure of the | | | | strapped to a table and tilted, with careful |
| severity of the illness and that is why blood | | | | measurements of heart rate and blood pressure |
| pressure is measured so often in acutely ill people. | | | | taken. Hormone levels in your blood may also be |
| Another potential cause of postural hypotension is | | | | measured to check that your adrenal glands and |
| blood pressure lowering drugs. The class of drugs | | | | nerves are working normally. |
| that is commonly used nowadays that may cause | | | | Failure of the adrenal glands can be treated by |
| a drop in standing pressure are alpha blockers, | | | | replacement of the missing hormones. If you |
| such as doxazosin. | | | | have a disease of the nerves then this can be |
| If you are older, and particularly if you have | | | | more difficult to treat, but you may respond to |
| diabetes, there may already be a tendency for | | | | drugs that stimulate the nervous system. You |
| your blood pressure to fall when you stand. | | | | may also find that wearing elastic stockings or an |
| If you get severe food poisoning and are sick and | | | | anti-gravity suit, or taking hormones that cause |
| have diarrhoea, you may lose large amounts of | | | | retention of salt and/or eating more salt can help. |
| fluid from your body. If you do get severe food | | | | Talk to your doctor for more information. |