What is it?
Secondary hyperparathyroidism is a condition in which too much parathyroid hormone (PTH) is produced. PTH is a chemical messenger, produced by the parathyroid glands to control calcium and phosphate levels in our blood and calcium levels in our bones.
Unlike primary hyperparathyroidism, which is caused by a problem within the parathyroid gland, secondary hyperparathyroidism occurs as a result of chronic kidney disease (CKD). Almost everyone whose kidney function has declined to the point where they need dialysis will have some level of secondary hyperparathyroidism.
What are the causes
Where are the parathyroid glands?
We usually have four parathyroid glands in our neck, located just behind or within the thyroid gland, and they control the amount of calcium in our blood and bones. We need calcium in our blood for our nervous and muscular systems to function properly, and calcium in our bones to keep them strong.
Three things cause increased production of PTH: low blood calcium, low levels of activated vitamin D, and high phosphate levels. All three occur in chronic kidney disease.
How does kidney disease affect the glands?
Healthy kidneys ‘activate’ Vitamin D so we can absorb calcium from our food. In advanced kidney disease the kidneys are unable to ‘activate’ vitamin D so less calcium is absorbed and blood calcium levels fall.
This triggers the parathyroid glands to overproduce PTH in an attempt to increase the amount of calcium in the blood. PTH then increases calcium absorption from food, but also takes calcium out of the bones, creating high blood calcium levels. This can coincide with another bone mineral imbalance – high levels of phosphorus in the blood (known as hyperphosphatemia). This happens when the damaged kidneys are unable to get rid of excess phosphate into the urine and it can cause itching and bone disease.
If left for too long, the parathyroid glands can remain overactive all the time. This is known as tertiary hyperparathyroidism. It's most commonly seen in people who've had kidney failure for a long time. In extreme cases, this can lead to excess calcium being deposited in blood vessels.
Symptoms
Symptoms of secondary hyperparathyroidism can include:
- Feeling thirsty and urinating more than usual
- Abdominal pain
- Tiring easily
- Muscle weakness
- Depression, forgetfulness or mild confusion
- Nausea, vomiting or loss of appetite
- Constipation
If left untreated, it may cause:
- Bone deformities, fractures and swollen joints
- Kidney stones
- bone pain or tenderness
- joint pain
- irregular heartbeat
- high blood pressure
Diagnosis
Your kidney doctors will do regular blood tests to check your balance of minerals. Secondary hyperparathyroidism would usually be diagnosed if your blood test showed:
- high levels of PTH
- high levels of blood calcium
A bone density X-ray (DEXA scan) may also be used to help detect bone loss, fractures or bone softening, and X- rays, CT ccans or ultrasound scans may be used to detect kidney stones or calcium deposits.
Treatment
Treatment for secondary hyperparathyroidism includes:
- Changes to diet to control the intake of phosphate
- Tablets including phosphate binders and vitamin D supplements
- Surgery to remove the parathyroid glands, either completely or leaving a small amount of gland in place
- A newer class of drugs called calcimimetics (cinacalcet, etelcalcitide) that mimic the action of calcium on tissues and suppress the production of PTH.
Treatment pros and cons
Parathyroid gland removal is an effective treatment, but comes with associated surgical risks and will need life-long drug therapy to control calcium levels post-surgery.
Dietary controls and the use of phosphate binders and calcimimetics are less invasive but this is a life-long treatment that can be associated with side effects.
- Don’t hesitate to speak to your kidney specialist or dialysis unit if you think you may have secondary hyperparathyroidism – or if you need help with any other aspects of your illness.
- You can also find lots of helpful tips, advice and information about exercise, diet, mental wellbeing and peer support in our How can I help myself? section
- Hyperparathyroidism - NHS https://www.nhs.uk/conditions/hyperparathyroidism/
- Lab Tests online:https://labtestsonline.org.uk/glossary/hyperparathyroidism
- National Kidney Federation: https://kidney.org.uk/help-and-info/medical-information-from-the-nkf-/medical-info-calcium-phosphate-index/
Reviewed April 2019
Hyperparathyroidism survey
In 2016, we conducted a survey about the treatment of hyperparathyroidism and what preference patients have for the treatment of this condition. The results of the survey helped shape and inform our submission to the National Institute of Health and Care Excellence (NICE) on Etelcalcetide for treating secondary hyperparathyroidism [ID908].
Our survey responses showed the importance of patient choice, with no definitive ‘favourite’ preference for the treatment of hyperparathyroidism. Many patients try a variety of treatments to find the one that suits them best. For some the only option is surgery, others want to avoid this at all costs. Treatment needs to be tailored to the individual as different treatments suit different patients. The National Institute for Clinical Excellence went on to approve etalcacetide as an option for treating secondary hyperparathyroidism.
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