The diagnosis of PHPT requires an elevated serum calcium level, with simultaneous demonstration PTH levels (or inappropriately (upper) normal levels of 10% of patients).
Measuring urinary calcium excretion over a 24 hour urine collection is important to rule out familial hypercalcaemic hypocalciuria. FHH is associated with low calcium excretion (lower than 150mg/day) and is not surgically treatable.
Primary Hyperparathyroidism (PHPT):
Primary hyperparathyroidism (PHPT) is caused by excessive secretion of parathyroid hormone (PT), which leads to increased bone resorption by osteoclasts (bone cells that reabsorb bone tissue), and increased calcium absorption by the kidneys and intestines.
It is the most common cause of raised calcium levels, and together with malignancy, is responsible for more than 90% of cases. Primary HPT occurs most commonly in patients over 50 years of age, and affects three times as many women as men. The incidence ranges from 3 - 20 cases per 1000 adults in different European countries. Other causes of hypercalcaemia may be grouped into those secondary to raised parathyroid hormone (PTH) levels and those mediated by other factors (see Table 1).
In approximately 85% of cases, PHPT is caused by a single adenoma (in the remaining cases, multiple glands are involved). Primary hyperparathyroidism can also be caused by parathyroid carcinoma, but this rare. Familial cases can occur either as part of the multiple endocrine neoplasia syndromes (MEN 1 or MEN 2a), familial isolated hyperparathyroidism (FIHPT) and familial hypocalciuric hypercalcemia (FHH).
Hypercalcaemia also causes dehydration, leading to a corresponding further increase in serum calcium concentration. It can also increase gastrin production, leading to increased acidity, so peptic ulcers may occur (groans), and neuropsychiatric symptoms can include depression, irritability and memory loss (moans). Other prominent symptoms include fatigue and weakness.
Most patients present with mild hypercalcaemia and very few overt symptoms, however, hypercalcaemic emergencies do exist. Severe hypercalcaemia (>3.75mmol/l) is considered a medical emergency, and can lead to coma and cardiac arrest. The effects of elevated calcium on cardiac muscle, meanwhile, include a shortened QT interval and increased risk of cardiac arrest.
Hypercalcaemia causes excess calcium production which exceeds renal capacity for reabsorption. Calcium therefore spills into urine, where it mixes with phosphate and leads to nephrolithiasis (stones).
Hypercalcaemia is a common clinical problem, affecting up to 35 cases per 1000 people in Europe. Calcium plays an important role in intracellular and extracellular metabolism, controlling processes such as nerve conduction, muscle contraction, coagulation and electrolyte regulation. As such the effects of hypercalcaemia are multiple and well summed up in the mnemonic 'Stones, Bones, Groans & Moans'.
For Further Information
Please feel free to contact us if you have
any questions regarding Thyroid & Parathyroid
Surgery, and if you would like to know more about Minimally Invasive Keyhole surgery.
Professor Kim has a special interest in Head & Neck Surgery and Endocrine Surgery and has undertaken supra-specialist training in these particular areas.
He also offers comprehensive treatment options for salivary gland disorders (including endoscopy of salivary glands), voice problems (including larynx injections & implants) and 'globus' throat symptoms (pain, tightness, cough, catarrh).
Based in London, Surrey and the South-East, we welcome referrals for both adult and children patients with problems relating to/affecting the Ear, Nose and Throat. These are some of the more common conditions we see and treat:
Prof Kim has recently written an article on the symptoms and diagnosis of 'Silent' Reflux - click here to find out more.
Further information on these and other conditions we treat can be found on the British ENT Surgeons Association website.
The article below, written by Professor Kim, discusses Hyperparathyroidism and the benefits of Minimally Invasive Keyhole surgery.
For more information on Minimally Invasive Keyhole Surgery and other thyroid conditions, please visit our London Thyroid website: www.london-thyroidsurgeon.co.uk
call us on: 07950 440 575
Dae Kim MBChB, BDS, MSc, FRCS (ORL-HNS), PhD
Consultant ENT & Specialist Thyroid Surgeon