Complaints & connections · borters.ch
As long as magnesium is short, potassium will not rise — and a low potassium with high blood pressure leads to the adrenal gland.
Also known as: hypokalemia · low potassium
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Potassium is what lets muscle and nerve cells hold their electrical charge. That applies to the thigh as much as to the heart muscle, and so a low value is always taken seriously. Almost all potassium sits inside the cells; only a tiny share floats in the blood — but that is the share that gets measured, and even small shifts show up. Potassium is lost almost always by one of two routes: through the kidney, usually because of water tablets, or through the bowel with vomiting, diarrhoea and regular use of laxatives. Added to these are causes rarely thought of: larger amounts of liquorice, an overactive adrenal gland, and shifts into the cells caused by insulin or by asthma inhalers. The shortage shows itself as muscle weakness, calf cramps, constipation and a stumbling heartbeat; often it stays silent and is noticed only in the lab. One point decides the success of any treatment and is nonetheless often missed: as long as magnesium is short at the same time, potassium can hardly be lifted — the kidney keeps letting it go. Correcting both together arrives somewhere; giving potassium alone fills a barrel with no bottom. And a low potassium together with high blood pressure is a trail of its own, leading to the adrenal gland.
The single most effective move when potassium will not rise. Without magnesium the kidney goes on losing, however much is topped up.
A low potassium with blood pressure that is hard to settle is the classic pointer to an overproduction of aldosterone — a cause that can be treated.
Dose, timing and type belong looked at — often a switch within the group solves it without anything being added. None of it changed on one’s own.
Potatoes, pulses, bananas, apricots, tomato purée, nuts and dried fruit supply plenty. With a limited kidney, though, the opposite applies — then the amount belongs discussed.
Both are rarely mentioned unprompted and explain some of the unexplained cases. Liquorice tea and some herbal mixtures count too.
Potassium can tip in both directions, and too much is as delicate as too little. A check after topping up belongs to the plan.
Potassium as tablet or infusion refills — the blood value rises quickly, the store inside the cells takes days. That is why the level often drops again after stopping: the shortfall is not truly made up yet. More important than refilling is the cause — water tablets, vomiting, diarrhoea, or a magnesium shortfall. As long as magnesium is missing, potassium will not hold, however much is given.
The normal range is 3.5 to 5.0 mmol/l; under 3.0 counts as marked, under 2.5 as threatening. Only about two per cent of the body’s potassium is in the blood — so a fall of 0.3 mmol/l already means a loss of several hundred millimoles in the body. Replacement through the vein is limited to ten to twenty millimoles an hour, because more strains the heart. Without correcting magnesium, potassium cannot be held.
The muscles announce themselves first, usually symmetrically and near the trunk. Cramps typically come at night.
This is the sign that gives the value its weight. Together with digitalis or with medicines that act on heart rhythm it counts for more.
By far the commonest cause. Thiazides and loop diuretics carry potassium out with them; potassium-sparing agents do the opposite.
This combination is a trail of its own. It leads to the adrenal gland and belongs clarified before simply topping up — especially when the blood pressure is hard to settle.
Three causes rarely asked about and which nobody volunteers. In larger amounts liquorice acts like an adrenal hormone.
What a deficiency makes visible on the body — skin, nails, tongue, eyes and nerves. The signs are unspecific: they show where to look, they prove nothing.
The value itself. It reads falsely low if the sample sits for long, and above all falsely high if the arm was squeezed at the draw — a single odd value is therefore repeated.
The value the treatment hangs on. Without it every dose of potassium stays ineffective, because the kidney goes on excreting it.
They show by which route the potassium is going. A high bicarbonate points more to vomiting or water tablets, a low one more to the bowel.
Kidney function decides how fast and how much may be replaced. With a limited kidney, potassium easily tips the other way.
Potatoes, pulses, bananas and dried fruit are the densest sources. With marked deficiency food is not enough — replacement is then targeted and monitored, because too much potassium is as dangerous as too little.
A potassium deficiency often cannot be corrected while magnesium is missing — the kidney otherwise keeps letting potassium go. So both are measured together.
Liquorice can lower potassium and raise blood pressure with longer use — one of the few really common herb effects.