The result arrives in a phone call that lasts ninety seconds. Bloods were fine, mostly. Kidneys grand. Cholesterol about the same as last year. “Your calcium is a bit high, but only a bit. We’ll keep an eye on it.”
Nobody is being careless. A mildly raised calcium is a common abnormal result, and most of the time it settles or turns out to be nothing much. But in a particular group of people, most of them women over 60, it is the only visible sign of a condition that quietly removes calcium from the skeleton for years and can be cured outright. The catch is that the number has to be chased to mean anything.
TL;DR
- Primary hyperparathyroidism is a common cause of a persistently raised blood calcium after 60, affecting around 1% of the population and clustering in women in their 60s and 70s.
- In a Stockholm population study of 10,190 people whose bloods met the biochemical criteria, only 52% had the diagnosis recorded clinically. The result was there; the name was not.
- A raised calcium needs a repeat test and then a PTH (parathyroid hormone) level measured on the same sample, not a vague plan to look again someday.
- Of 43,399 people newly diagnosed in a US cohort, 51.3% already had bone or kidney damage at diagnosis, and a third of the rest developed it within roughly 17 months.
- Surgery cures over 95% of cases, but the benefit in mild disease after 65 is modest, so the goal is a proper diagnosis and assessment rather than an automatic operation.
- The Irish bottleneck: 24,446 adults were waiting for a first endocrinology outpatient appointment at the end of August 2026, and 7,121 of them had been waiting over 18 months.
Four glands the size of grains of rice
Behind the thyroid, in the front of the neck, sit four parathyroid glands. They have one job: keeping blood calcium inside a narrow band. When calcium dips, they release parathyroid hormone, which pulls calcium out of the skeleton, holds on to more of it in the kidneys, and helps the gut absorb more from food. When calcium rises, they go quiet.
Primary hyperparathyroidism is what happens when one of those glands stops listening. Usually a single benign growth, an adenoma, keeps producing hormone regardless of how much calcium is already circulating, and the skeleton becomes the supply depot for a signal that never switches off. Prevalence is around 1% of the general population. A population study in the Veneto region of Italy found a female-to-male ratio of 2.55 across 5,276 new cases, a median age of 65, and the sharpest female predominance in the 50 to 54 age group. Which is to say it begins at menopause.
The result that goes unnamed
The most useful recent evidence comes from Stockholm, where researchers worked through 578,227 parathyroid hormone measurements taken from 176,780 people between 2006 and 2020. Applying strict biochemical criteria, they identified 10,190 patients who met the definition. Over that period, the age- and sex-adjusted incidence rose from 2.81 to 4.28 per 10,000 person-years, with the steepest increase among women aged 70 and over, and point prevalence rose from 0.35 to 4.76 per 1,000 people.
The finding that matters for anybody reading their own blood results is this: a clinical diagnosis was documented in 5,346 patients, which is 52%. Just over half. The biochemistry was sitting in the record, meeting the criteria, and in nearly half of cases nobody joined it up. Of those who did receive the diagnosis, 52% went on to have surgery.
Ireland has no equivalent dataset. Applying that prevalence figure to the 4,300,635 adults aged 18 and over in the CSO’s April 2026 population estimates would suggest somewhere in the region of 20,000 people, concentrated heavily among the 1,911,739 adults aged 50 and over. That is an applied estimate from another country’s data, so read it as an order of magnitude rather than a headcount.
Why “no symptoms” is misleading
The old teaching rhyme was “stones, bones, moans and groans”: kidney stones, bone pain, abdominal upset and low mood. That describes advanced disease, which is now uncommon in countries that do routine bloods. Most people found today are labelled asymptomatic.
Two things complicate that label. The first is that the symptoms which do occur are the ones everybody over 60 has learned to blame on age. NICE guidance uses the phrase “chronic non-differentiated symptoms” and lists them plainly: fatigue, mild confusion, bone, muscle or joint pain, anxiety, low mood, irritability, apathy, insomnia, frequent urination, increased thirst and digestive problems. Not one of those items sends a person to a GP saying “I think this is my parathyroid glands”.
The second is that the damage does not wait for symptoms. A cohort study published in JAMA Surgery in 2026 followed 43,399 adults with a new biochemical diagnosis, mean age 67.9 and 78% female. At diagnosis, 22,279 of them, or 51.3%, already had end-organ damage: osteoporosis, a fracture that happened without major trauma, kidney stones, or chronic kidney disease at stage 3 or worse. Among the 21,120 who did not, 6,762 (32.0%) went on to develop it after a median of 516 days. Only 19.9% of those with established damage had surgery.
What should actually happen after a raised calcium
The clearest published pathway is NICE guideline NG132, which is written for primary care and is specific about the sequence.
- Measure albumin-adjusted calcium if there are symptoms of high calcium, osteoporosis or a previous fragility fracture, a kidney stone, or an incidental result of 2.6 mmol/L or above.
- Repeat it at least once if the first reading is 2.6 mmol/L or above, or 2.5 mmol/L or above with other features present.
- Measure PTH once calcium is raised on at least two separate occasions, with calcium measured again on the same sample.
- Seek specialist advice if PTH sits above the midpoint of the reference range alongside that raised calcium. A PTH below the lower limit with a high calcium points somewhere else entirely, including cancer, and needs different investigation.
- After diagnosis, the assessment includes kidney function, a DXA scan of the lumbar spine, hip and forearm, and an ultrasound of the kidneys and urinary tract.
That forearm measurement is not an afterthought. Parathyroid hormone preferentially strips the type of bone found there, so a DXA covering only hip and spine can look reassuring while the disease is plainly visible at the wrist.
The Irish vitamin D complication
Before anybody panics about a raised PTH, there is a very Irish explanation to rule out first. When vitamin D is low, the gut absorbs less calcium and the parathyroid glands work harder to compensate. The result is a raised PTH with a normal calcium, which is a different problem with a different fix: replace the vitamin D.
That matters here more than most places. TILDA measured vitamin D in 5,356 community-dwelling adults aged 50 to 98 and found 13.1% were deficient, with deficiency more common in winter, among people who took no supplement, in those living alone and in people over 80. NICE accordingly says to measure vitamin D in anyone with a probable diagnosis and to supplement where needed.
Why the laboratory matters
There is one more wrinkle worth knowing before you worry about a borderline result. PTH assays are not standardised between manufacturers. In a study from a UK clinical biochemistry service, 55 patients identified as having normocalcaemic primary hyperparathyroidism on an Abbott platform had the identical frozen samples re-analysed elsewhere. On the Roche platform, 16 (29.1%) still met the definition. On the Siemens platform, 11 (20.0%) did. More than half came back entirely normal on both. Those three platforms are used by over 85% of UK clinical laboratories.
A follow-up by the same group found that age-specific reference intervals improved agreement considerably. The practical takeaway: ask that repeat tests be done by the same laboratory, and keep your own copies of the numbers with their reference ranges attached.
Surgery: curative, but be honest about the size of the benefit
Removing the overactive gland is the only cure, and both the targeted keyhole operation and the traditional four-gland exploration achieve cure rates above 95%. Complications are uncommon but real: bleeding, infection, injury to the nerve supplying the voice box, and low calcium afterwards. NICE recommends referral to a surgeon with parathyroid expertise for anyone with symptoms of high calcium, with end-organ disease such as kidney stones, fragility fracture or osteoporosis, or with an adjusted calcium of 2.85 mmol/L or above, and says referral may be considered even without those features.
What does surgery buy an older adult? The largest relevant dataset covered 210,206 Medicare beneficiaries with the condition, mean age 75, of whom 78.8% were women. Those who had surgery within a year had a lower adjusted rate of any fracture (hazard ratio 0.78) and of hip fracture (0.76), an absolute reduction in fracture risk of 1.2% at two years, 2.8% at five and 5.1% at ten. The benefit did not differ by age, sex or frailty.
Set against that, a randomised trial published in 2026 allocated 102 patients aged 65 and over with mild disease and reasonable bone density, median age 71, to surgery or observation at Lund University Hospital. After two years, total hip bone density had risen 1.3% in the surgery group and fallen 1.4% in the observation group, and lumbar spine density had risen 4.6% versus 0.2%. Both differences were significant and both are small. The trialists concluded that their results “may caution any expansion of the indication for parathyroid surgery” in this age group. A separate study of 40,231 adults found no difference in new depression between early surgery and watchful management, so nobody should promise an operation will lift mood. The honest position is a cure worth having when there is end-organ damage or a markedly raised calcium, and a much closer call in mild disease.
The Irish bottleneck, and what to do about it
Getting assessed is where Ireland struggles. National Treatment Purchase Fund open data for 27 August 2026 records 24,446 adults waiting for a first endocrinology outpatient appointment, of whom 7,121, or 29%, had been waiting more than 18 months. For comparison, general surgery had 32,492 adults waiting and just 266 of them, 0.8%, beyond 18 months. Endocrinology is a small speciality carrying a very long tail.
Delay then compounds. In a review of 266 people who eventually had parathyroid surgery, those aged 65 and over waited a median of 11.3 months from biochemical diagnosis to operation compared with 7.5 months for younger patients, and only 37.8% of the group had received the complete recommended work-up beforehand. Older patients were more often operated on because of bone disease or reduced kidney function, which is to say because something had already been lost.
Practical steps that are entirely within your control:
- Ask for the repeat to be booked, with a date, rather than left as “we’ll check it again sometime”.
- Ask whether PTH and vitamin D were measured on the same sample as the calcium. A PTH without a simultaneous calcium is hard to interpret.
- Request a printed copy of every result with its reference range, and note which laboratory did it.
- Mention your medicines. Long-term lithium reduces the glands’ sensitivity to calcium, and both lithium and thiazide diuretics affect the urine calcium tests used during assessment.
- Connect the dots out loud. A past kidney stone, a fracture from a minor fall or unexplained osteoporosis are what move you up the pathway, so say them at the appointment.
- Use the entitlements you have. Everyone aged 70 and over qualifies for a GP visit card with no means test, which removes the cost of the repeat consultation this whole process depends on.
A number is not a diagnosis, and silence is not reassurance
The lesson in the Stockholm figures is not that doctors are missing things on purpose. It is that a slightly raised calcium is easy to file under “nothing much” at every single step, and that filing it there a few years in a row is how people meet this condition through a fractured wrist instead of a blood test. If you have been told your calcium is a little high, asking what the plan is makes you sensible, not alarmist. One repeat test and one PTH level is a modest request.
At Críonna Health we write about the parts of ageing that get managed by inference rather than examination. For related reading, see our guides to understanding your blood test results after 50, bone health and preventing osteoporosis, spinal fragility fractures after 70 and kidney stones after 50.
This article is for general information and is not a substitute for individual medical advice. If you have been told your blood calcium is raised, discuss it with your GP.
📷 Photo by Anna Keibalo on Unsplash
