Water pills are trusted – but there is a catch
They also promote the flow of urine, which can potentially deplete the body of its essential salts
When reading of the latest, invariably costly, “wonder drug”, it is only sensible to “wonder” what its adverse effects might turn out to be. Much better, where possible, to stick with the tried and tested drugs that many years of experience have shown to be safe and effective. And there is no more tried and tested class of drugs than the thiazide diuretics (or “water pills”), bendroflumethiazide and chlorthalidone, originally introduced more than 60 years ago. Being cheap, well-tolerated and (very) familiar, they are much the most widely prescribed medication for reducing the risk of stroke and heart problems in those with raised blood pressure.
There is, however, a catch about which those taking them should be aware. The thiazides have a dual mode of action, reducing blood pressure by dilating the blood vessels and also promoting the flow of urine – thus reducing the amount of fluid in the circulation. That increased flow, besides facilitating the excretion of waste products, can also potentially deplete the body of its essential salts, sodium and potassium.
Last week the British Medical
Journal reported that this occurred
more commonly than previously realised, with 15 per cent of those taking thiazides being found to have low levels of sodium in the blood (hyponatremia). This may result variously in excessively low blood pressure predisposing to falls, fatigue, weakness and cognitive impairment. The hazards of low potassium in the blood are more serious still, predisposing to potentially fatal heart rhythm disturbances. Thiazides can also raise the risk of diabetes.
There are several possible causes of all these problems, so the contributory role of thiazide-induced salt depletion may be overlooked – not least, as noted, because they are so widely perceived as being safe and well-tolerated. Gratifyingly, these insidious adverse health effects can be avoided by the simple expedient for those taking thiazides of ensuring they have regular tests of their blood biochemistry.
Valves like Jagger
I am remiss, it is suggested, in oversimplifying the question of the relative merits, for those incapacitated by a tight aortic valve, of the standard open heart operation versus a TAVI (transcatheter aortic valve implantation). The TAVI is certainly the less traumatic procedure in obviating the need to “open up” the chest and is thus the preferred option for the frail and ill. The issue of its durability, however, remains unresolved – certainly compared to the standard operation that can be reliably expected to last for 15 years or more.
Mick Jagger, 75, was last week seen dancing around as he recovered from a TAVI procedure, but as several readers observe, the potential hazard for such fit and healthy patients is that they cannot then have another.
Thus, were it to fail within a few years, Jagger would then require open heart surgery, by which time his circumstances might be very different.
Cardiac surgeon Joseph Zacharias of Blackpool’s Royal Victoria Hospital points out that he, along with colleagues elsewhere, has modified the open heart operation so it is no longer necessary, as previously, to split the sternum to gain access. This necessitates only a couple of additional days in hospital compared to the TAVI, with the almost cast-iron certainty that it will endure.
‘I’m an insect magnet’
This week’s medical query comes courtesy of Mr RS from Leeds, who is a magnet for every type of biting insect – unlike his wife to whom they are apparently completely indifferent. “They crawl up my arms and legs and down my neck to molest me,” he writes, against which long socks and insect-repellent clothing offer only modest protection. He suspects they are attracted by his “flavour”, prompting him to speculate that some change in his diet might deter them. Perhaps readers of this column may have some suggestions?