A High Potassium with a Low Sodium
Each of these on its own is minor and common. Together they are the electrolyte signature of adrenal insufficiency, which is why the pair deserves reading as one finding instead of two unremarkable values. It is characteristically diagnosed late, because the symptoms — tiredness, weight loss, dizziness on standing, feeling unwell in a vague and worsening way — sound like almost anything.
The pattern on your report
- Potassium High · mild Key
- Sodium Low · mild Key
- Morning cortisol Low Key
- Glucose Low-normal Key
- Urea High-normal Supporting
Printed as: Urea in mmol/Lor mg/dLMorning cortisol in nmol/Lor ug/dL— Strong daily rhythm, so a morning sample is required and a random one means little.Glucose in mmol/Lor mg/dLPotassium in mmol/Lor mEq/L— Confirm on a clean sample before acting, since a difficult draw raises it in the tube.Sodium in mmol/Lor mEq/L— Falls here because aldosterone is no longer telling the kidney to retain it.
Why the numbers look like this
The adrenal glands make two hormones that matter here. Cortisol supports blood pressure, glucose and the response to stress. Aldosterone tells the kidney to retain sodium and discharge potassium.
When the glands themselves fail, both are lost. Sodium is no longer retained so it falls; potassium is no longer discharged so it rises. That combination gives the pair its specificity, and it explains why two values moving in opposite directions say more than either moving alone.
When the problem sits in the pituitary instead, only cortisol is affected, because the kidney controls aldosterone and the pituitary does not. Sodium still falls, but potassium stays normal. So the potassium tells you which gland is at fault.
The danger lies in what happens under stress. An infection, an injury or an operation demands a surge of cortisol that cannot be produced, and blood pressure collapses. That is an adrenal crisis, and it can be the presenting event in someone whose blood tests had been drifting for a year.
Not being flagged is not the same as normal
Cortisol has a strong daily rhythm, peaking early and falling through the day, so a random level is close to uninterpretable and only a morning sample will do. Even then a single value cannot exclude the diagnosis, which is why a stimulation test is used to confirm it. One practical point matters more than any of this: steroid treatment taken for other reasons, including inhaled and joint injections, suppresses the glands and produces the same vulnerability, so the drug history changes the interpretation entirely.
What else on the report can hide this
A morning cortisol is the first step and a stimulation test is the confirming one. Between them they answer the question, and neither is elaborate.
Glucose belongs in the same check because cortisol deficiency lowers it, particularly in children and during illness.
Calcium is sometimes raised, which is a less well known feature and another reason the picture can look confusing.
Once the diagnosis is established, the cause matters. Autoimmune destruction is the commonest in most populations, and it travels with other autoimmune conditions, so thyroid function and a check for celiac disease and diabetes are reasonable. Tuberculosis remains a leading cause worldwide.
The practical part deserves stating plainly, because it is the part that actually protects people: adrenal insufficiency is treated with replacement that works well, and the treatment is entirely compatible with a normal life. What changes outcomes is knowing to increase the dose during illness, carrying an emergency injection, and wearing something that identifies the condition. People die of this from an untreated crisis, not from the condition itself.
What usually causes it
Listed from most to least common — not from most to least serious.
- Very common
Autoimmune adrenal insufficiency
The commonest cause in most populations. Travels with other autoimmune conditions, so thyroid, celiac and diabetes screening are reasonable alongside.
- Very common
Recently stopped or reduced steroid treatment
Suppressed glands that have not yet recovered. Includes inhaled steroids and joint injections, which people do not always count as steroids.
- Common
Medication affecting potassium
ACE inhibitors, receptor blockers and potassium-sparing diuretics raise potassium directly, so they can imitate part of this picture without any adrenal problem.
- Common
A hemolyzed or difficult sample
Raises potassium in the tube. Worth excluding with a clean repeat before anything follows from it.
- Common
Kidney impairment
Raises potassium by reducing its excretion. The creatinine and eGFR separate it from an adrenal cause.
- Uncommon
Pituitary disease
Cortisol low but aldosterone preserved, so the sodium falls while the potassium stays normal. The potassium is what points to which gland.
- Uncommon
Tuberculosis of the adrenal glands
A leading cause worldwide. Relevant exposure or origin, and imaging may show calcified glands.
- Rare
Adrenal hemorrhage or infarction
Sudden, with abdominal or flank pain and collapse. This presents as a crisis rather than as a drifting blood test.
- Rare
Congenital adrenal hyperplasia
Usually identified in childhood, though milder forms surface later. A different diagnostic pathway.
What is usually checked next
- A morning cortisol The first step, and the timing is what makes it interpretable given the daily rhythm.
- A stimulation test Confirms the diagnosis, which a single cortisol level cannot do on its own.
- A steroid history including inhaled and injected forms Suppression from treatment produces the same vulnerability and changes the interpretation completely.
- Repeat potassium on a clean sample, with kidney function Excludes a tube artifact and reduced excretion, which between them explain most raised potassium levels.
- Thyroid function, celiac serology and glucose The autoimmune conditions that cluster with this one, and cortisol deficiency lowers glucose in its own right.
When to seek care sooner
- Emergency Collapse, severe weakness, or confusion during an illness
- Emergency Vomiting with abdominal pain and dizziness
- Emergency Palpitations or an irregular heartbeat with a high potassium
- Same day Dizziness or fainting on standing
- Soon Unintentional weight loss with increasing tiredness
- Soon Darkening of skin creases, scars, or the inside of the mouth
Questions worth bringing to your appointment
- Should a morning cortisol be checked given these two results together?
- Have I taken any steroid recently, including inhalers or injections?
- Could my potassium be raised by a medication or by the sample itself?
- If this is confirmed, what do I do when I am unwell?
- Should I carry an emergency injection and identification?