A potassium deficiency often gives muscle weakness, fatigue and sometimes an irregular heartbeat. In older adults the best-known cause is the use of water pills. Potassium is kept tightly regulated in your blood, so both a too-low and a too-high value need attention.
We see that people worry about their heart when the word potassium comes up. That is understandable, and below we explain calmly how it works.
Potassium is a mineral your body needs for the signals in your muscles and your heart. It is in many foods, but the balance in your blood is mainly regulated by your kidneys and by hormones. With age that balance is disturbed more easily, certainly combined with medicines.
In this piece we therefore look separately at what a deficiency means in people over 60. We discuss the complaints, the causes and what your potassium value in the blood can tell you.
What are the symptoms of a potassium deficiency?
The complaints of a potassium deficiency, also called hypokalaemia, are usually muscle weakness, fatigue, cramp and sometimes palpitations. With a larger deficiency the heartbeat can become irregular. The complaints are non-specific, so they also fit other causes.
| Where you may notice it | Example |
|---|---|
| Muscles | Weakness, cramp in arms or legs |
| Energy | Fatigue, listlessness |
| Heart | Palpitations or irregular beat |
| Digestion | Constipation |
Do you notice these complaints and use water pills? Then having it checked is wise.
Why are older adults at extra risk of a potassium deficiency?
The most common cause in older adults is the use of certain water pills, which remove potassium via the kidneys (Viera and Wouk, 2015). Long-lasting diarrhoea or vomiting can also lower potassium. The Dutch Farmacotherapeutisch Kompas describes that some water pills spare potassium and others do not.
That is why it is important to know which type of medicine you use. Never stop a water pill yourself, but discuss it with your GP.
Do you use medicines that act on the kidneys? Then also read medication and your kidneys.
What does your potassium value in the blood mean?
Potassium is held tightly within a narrow range in your blood, because it is important for your muscles and heart rhythm. A value below that range is called a deficiency, a value above it an excess. Both can cause complaints, so the direction of the change matters.
You can have your potassium measured via the potassium blood value. A doctor registered in the Dutch BIG register reviews the result and places it in context.
The Dutch Nutrition Centre (Voedingscentrum) names vegetables, fruit, potatoes and legumes as sources of potassium. With a healthy kidney function, varied eating helps keep the balance up.
What can you do yourself if in doubt?
With persistent muscle weakness or palpitations it is wise to have it looked into rather than taking potassium supplements yourself. Too much potassium can be dangerous, certainly with a slower kidney function.
My advice: discuss complaints and your medicine use with your GP. A blood test can support the conversation.
Want the bigger picture? Then read the pillar on vitamins and minerals after 60 or the piece on low sodium.
Which foods contain potassium?
Potassium is in many vegetables, fruits and potatoes. Bananas, oranges, potatoes, spinach, legumes and tomatoes are well-known sources. With a healthy kidney function, varied eating helps keep your potassium up.
Note: if your kidneys work less well, too much potassium can actually become a problem. Then a different advice applies than for someone with healthy kidneys.
So discuss with your GP what is suitable for you, certainly if you have kidney problems or use medicines that affect potassium.
What does an out-of-range potassium value mean?
Because potassium is held within a narrow range, both the level and the direction of the change matter. A low value can fit water pills, diarrhoea or vomiting. A high value often links to the kidneys or to certain medicines.
What the result means for you depends on your complaints and your medicines. Potassium is therefore usually assessed together with kidney function.
An out-of-range value is no reason to panic, but it is a reason to have it looked at calmly. Your GP can decide whether further steps are needed.
Frequently asked questions
Below are the questions we hear most often about potassium later in life.
References
- Viera AJ, Wouk N. Potassium Disorders: Hypokalemia and Hyperkalemia. Am Fam Physician. 2015;92(6):487-495. PMID: 26371733.
- Netherlands Nutrition Centre (Voedingscentrum). Potassium. Accessed 2026. voedingscentrum.nl.
- Dutch Pharmacotherapeutic Compass (Farmacotherapeutisch Kompas). Diuretics. Accessed 2026. farmacotherapeutischkompas.nl.
Would you like to have your potassium and other values checked at a calm moment, without first booking an appointment with your GP? At Levenswijs Health you can. Every result is reviewed by a doctor registered in the Dutch BIG register. A blood test does not provide a diagnosis. For treatment decisions, always discuss your results with your GP.
Frequently asked questions
What are the symptoms of a potassium deficiency?
Often these are muscle weakness, fatigue, cramp and sometimes palpitations. With a larger deficiency the heartbeat can become irregular. The complaints are non-specific, so a blood test gives direction but does not provide a diagnosis.
Can water pills cause a potassium deficiency?
Yes. Some water pills remove potassium via the kidneys and can cause a deficiency, while others spare potassium. So know which type you use. Never stop yourself, but discuss it with your GP.
Is a too-high potassium also a problem?
Yes. Potassium is tightly regulated in the blood, and both a too-low and a too-high value can cause complaints. Especially with a slower kidney function, caution with supplements is important. Discuss your value with your GP.
Do I need a referral to have potassium measured?
No. At Levenswijs you can have your potassium measured without a referral. The result is reviewed by a doctor registered in the Dutch BIG register. For treatment, your GP remains your point of contact.
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