Diagnosis of Hyperparathyroidism

Diagnosing Primary Hyperparathyroidism is based on appropriate laboratory workup

Appropriate suspicion

First it is important to understand the basics of parathyroid disease. The finding of high calcium levels in the blood on routine testing or in the evaluation of postmenopausal women with osteoporosis is typically the initial clue to a physician of the diagnosis of primary hyperparathyroidism. Patients with excessive urination, dementia or confusion, pre-menopausal bone loss, men with bone loss, recurrent kidney stones, endocrine syndromes such as MEN1 and MEN2 should raise the suspicion for high calcium levels. The endocrinologists at Houston Thyroid an Endocrine are experts in parathyroid disease. 

Find high blood calcium levels

The total serum calcium level is generally part of most routine blood work.  It  should be adjusted for the level of blood albumin to exclude nutritional changes in calcium levels of patients.  
Corrected or adjusted total calcium= (measured total calcium in mg/ deciliter)+[0.8×(4.0−patient's serum albumin concentration in g/deciliter)] 
Measurement of ionized calcium can be more accurate for diagnosis in some patients: thos with hyperalbuminemia, thrombocytosis, Waldenström's macroglobulinemia, and certain cancers like myeloma. These patients may have high total serum calcium, but normal levels of ionized serum calcium (artifactual hypercalcemia).

Check parathyroid hormone 

Parathyroid glands make parathyroid hormone and this hormone controls calcium levels. Abnormal levels are associated with certain disorders. 

Primary hyperparathyroidism:  An elevated or "normal" level of PTH  simultaneous with an elevated calcium level generally clinches a diagnosis of primary hyperparathyroidism.  However, these laboratory findings may also occur with certain medications like lithium or diuretics like thiazides, tertiary hyperparathyroidism associated with end-stage renal failure, and familial hypocalciuric hypercalcemia (FHH).  the endocrinologists at Houston Thyroid and Endocrine will do a complete medical and family history to assess these possibilities. 

Normocalcemic primary hyperparathyroidism: normal corrected calcium or ionized serum calcium and an elevated level of PTH in patients with no other causes of secondary hyperparathyroidism.

Cancer-associated hypercalcemia: A low or undetectable PTH level rules out primary hyperparathyroidism and raises this possibility.  

Familial hypocalciuric hypercalcemia:  Once the diagnosis of primary hyperparathyroidism has been established, this familial form, accounting for about 5% of cases, should be considered. 

Multiple Endocrine Neoplasia: This diagnosis is considered in certain patients: young age (<30 years) at diagnosis; a family history of hypercalcemia, neuroendocrine tumors, or both; the presence of specific skin lesions 

 Parathyroid carcinoma:  very rare diagnosis considered in patients with a neck mass, markedly elevated levels of serum calcium >14 mg per deciliter and PTH 3 to 10 times the upper limit of normal, especially in men.

Other testing

Laboratory testing should include assessment of kidney function, serum 25-hydroxyvitamin D. Levels of 25-hydroxyvitamin D below 20 ng per milliliter are common, probably because of its increased conversion to 1,25-dihydroxyvitamin D and this may worsen the disease by increasing PTH secretion. The 24-hour urinary calcium and creatinine level could be measured to rule out familial hypocalciuric hypercalcemia.  Renal ultrasound is recommended if there are kidney stones since 7% of patients with asymptomatic primary hyperparathyroidism may have stones show on the ultrasound. Bone mineral density should be measured. Regular xrays of skeleton are not recommended. Neck imaging is not indicated for diagnosis, but it is useful for disease localization.

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