Table 5.

PHPT: Key points and what is new.

A. Diagnosis

1. Confirmed if serum calcium is elevated (total calcium corrected for albumin or elevated ionized calcium) in the presence of an elevated or inappropriately normal PTH in the absence of conditions mimicking PHPT (thiazide diuretics or lithium) and FHH.

2. FHH – Three variants now identified. Confirmed by DNA analysis of CaSR gene, Gα11 gene or AP2S1 genes. Suspected if CaCrCR <0.01. However in 20% of FHH cases CaCrCR can overlap with PHPT and is 0.01-0.02.

3. Consider familial PHPT in children and adults <35 years of age and DNA analysis (MEN1 gene, RET oncogene, HRPT2 gene) in the presence of:

a. Family History of hypercalcemia

b. Prior unsuccessful parathyroid surgery in patient or relative

c. Hypercalcemia identified at young age (<25yrs) in patient or relative

d. Absence of symptoms of hypercalcemia

e. CaCrCR <0.02

B. Imaging:

1. Imaging is not used for the diagnosis of PHPT, which is based on biochemical profile.

2. Identification of abnormal parathyroid tissue is enhanced with single photon emission computed tomography (SPECT) study in combination with a computed tomography (CT) study and is particularly valuable in repeat surgical cases.

3. Ultrasound, 99m Tc-sestamibi scintigraphy continue to be useful localization tools, however, they can miss small adenomas and hyperplasia.

4. Additional imaging or localization tools for those failing surgery or suspected of having an ectopic parathyroid gland include CT scans, MRI (Magnetic Resonance Imaging), 11C-Methionine PET/CT Parathyroid Scintigraphy. Selective venous sampling should only be performed when required for remedial exploration.

C. Presentation:

1. In developed countries – approximately 85% of patients present with asymptomatic disease. Twenty % present with renal complications (kidney stones, nephrocalcinosis), skeletal complications (fracture, osteitis fibrosa cystica, bone pain) or symptomatic hypercalcemia.

2. In developing countries the majority of patients present with symptomatic disease.

D. Indications for Parathyroid Surgery

1. All symptomatic PHPT

2. Asymptomatic PHPT – surgery is a valuable option particularly in those meeting criteria for surgical intervention.

E. Medical Management

1. Vitamin D deficiency/insufficiency should be corrected and is effective in lowering serum PTH without further elevating serum calcium. Correct serum 25OHD to >50nmol/L.

2. Amino-bisphosphonates are effective in preventing decreases in BMD and lowering bone remodelling.

3. Cinacalcet is effective in lowering serum calcium and should be considered for symptomatic PHPT when surgery is not an option. Amino-bisphosphonates may be used in combination with cinacalcet in selected patients.

4. Data with medical therapy currently is short-term and insufficient to justify medical therapy as an alternative to surgery. There is no fracture data with any of the existing medical therapies.