PHP (primary hyperparathyroidism)

Primary hyperparathyroidism (PHP) may be defined as an excessive secretion of parathyroid hormone (PTH) from the parathyroid gland (in the absence of a known or recognised stimulus) resulting in hypercalcaemia (intrinsic abnormal change). (1).

• it is the third most common endocrine disorder
• the most common cause of hypercalcaemia in the ambulatory setting (2)
• PHP should be suspected in any person with an elevated serum calcium level but the condition may equally occur in normocalcaemic patients with co-existent vitamin D deficiency
• is a disorder of one or more of the parathyroid glands
  • parathyroid gland becomes overactive and secretes excess amounts of parathyroid hormone, causing hypercalcaemia, hypophosphataemia and hypercalciuria
  • most common cause of primary hyperparathyroidism is a non-cancerous tumour (an adenoma) in one of the parathyroid glands (4)

The accurate incidence of PHP is unknown but according to current data a prevalence of 1-4/1000 in the general population is suggested (2,4)

• women are twice as likely to be affected as men and the peak incidence is in women between 50 and 60 years of age (2,4)
• similar incidence is seen in both men and women before 45 years of age (3)
• in young people of either sex, it is important to investigate possible multiple endocrine neoplasia.

With the use of routine calcium screening in Western countries, the clinical profile of primary hyperparathyroidism has shifted from a symptomatic disease, to one with subtle or no specific symptoms (“asymptomatic” primary hyperparathyroidism). The symptomatic variant is still predominant in the developing world (3).

Clinical features associated with primary hyperparathyroidism (4):

• are predominantly brought about by hypercalcaemia and include thirst and increased urine output, gastrointestinal symptoms such as constipation, and effects on the central nervous system such as fatigue and memory impairment
• long-term effects include kidney stones, bone-related complications such as osteoporosis and fractures, and cardiovascular disease

Reference:

• (1) Fraser WD. Hyperparathyroidism. Lancet. 2009;374(9684):145-58.
• (2) Pallan S, Rahman MO, Khan AA. Diagnosis and management of primary hyperparathyroidism. BMJ. 2012;344:e1013
• (3) Marcocci C, Cetani F. Clinical practice. Primary hyperparathyroidism. N Engl J Med. 2011;365(25):2389-97
• (4) NICE (May 2019). Primary Hyperparathyroidism.