Feature ArticleSimplifying the Complexity of Primary Hyperparathyroidism
Introduction
Patients with primary hyperparathyroidism (PHPT) have abnormally elevated calcium (Ca) and parathyroid hormone (PTH) levels with respect to each other. In the United States, PHPT is the most common cause of hypercalcemia encountered in ambulatory care.1 About 100,000 patients are diagnosed annually, producing an annual US incidence of < 10 per 100,000 and prevalence of up to 1%.2 Before middle adulthood, the prevalence of PHPT is similar in men and women but is more common after age 65. Postmenopausal women have the highest incidence of PHPT.2
PHPT can have significant, insidious effects on the body, most commonly increasing bone turnover and decreasing bone mineral density (BMD). Failure to correct bone abnormalities has a negative impact on fracture risk. Severe bone disease, known as osteitis fibrosa cystica (OFC), only occurs in < 3% of patients in the US.3 PHPT affects the central nervous, cardiac, renal, and gastrointestinal systems, yet patients may present asymptomatically with elevated Ca and PTH levels. Abnormalities in serum Ca and PTH levels often provoke questions from providers regarding the best approach to diagnostic testing and management. Prompt diagnosis and appropriate treatment of patients with parathyroid abnormalities is critical to mitigate adverse outcomes from unrecognized, chronic disease.
Symptomatic patients with mild PHPT improve after parathyroidectomy.1 However, management of patients with mild, asymptomatic PHPT can be challenging. Although medical management is an option for patients with PHPT, surgery is indicated for patients who meet surgical criteria and is the only cure. The benefit of parathyroidectomy on body mass index, lifestyle, and psychological function as compared with no surgery is that surgery is a cost-effective treatment with minimal risk for complication from a single procedure.4
Section snippets
Parathyroid Glands
The parathyroid glands are pea-sized glands located behind the thyroid gland. Expected anatomic findings upon exploration of the neck reveal 4 parathyroid glands, but ectopic parathyroid glands can be found in the thyroid, high in the neck or carotid sheath, in the retroesophageal space, and within the thymus or mediastinum. Parathyroid glands produce PTH, also known as parathormone, or PTH-intact. All parathyroid glands that hypersecrete PTH are enlarged, sometimes to the size of a lima bean
Definition
Hyperparathyroidism occurs when serum PTH levels are elevated relative to serum Ca levels. Although hyperparathyroidism is associated with abnormal Ca metabolism, 2%-5% of patients are asymptomatic.1 The diagnosis may be made upon incidental finding of hypercalcemia during routine blood tests or when routine BMD testing is abnormal.
Mild PHPT includes patients who have normal Ca levels with elevated PTH or elevated Ca levels with an inappropriately normal or high-normal PTH.1 The most common
Clinical Presentation
In the US, approximately 15%-20% of patients with PHPT present with nephrolithiasis, a diagnosis often made in the primary care setting.13 Patients with PHPT may have no symptoms, but commonly mild symptoms. PHPT can be missed, even with expert history-taking skills and physical exam techniques. Normal physical findings can be seen in PHTH as 2%-5% of patients are truly asymptomatic.1
Symptoms of hypercalcemia include anorexia, nausea, constipation, insomnia, arthritis, polydipsia, and polyuria,
Laboratory Data
The 2 laboratory tests used to determine serum Ca levels are total serum Ca or an ionized serum Ca.14 In the serum, 40% of Ca is bound to serum proteins, predominantly albumin, so serum albumin levels must be considered in the interpretation of a serum Ca level.15 If a patient’s serum albumin level is low, then the associated total serum Ca level is also low, as there is less protein to which Ca can bind. If the patient’s albumin levels are below normal, a mathematical calculation is used to
Radiography
Despite the protective effect of PTH on cortical bone, radiographic changes demonstrate diffuse demineralization and pathologic fractures usually seen in the long bones of the extremities.
Subperiosteal bone erosions of the distal phalanges and lateral aspects of the middle phalanges and a salt-and-pepper appearance of the skull are radiologic findings consistent with severe PHPT.3 Screening for osteoporosis facilitates earlier diagnosis of PHPT. Although fractures are not common in PHPT,
Medical Treatment
Controversy exists regarding treatment for the 2%-5% of patients who have biochemically confirmed PHPT but lack overt signs and symptoms.13 Medical management of these patients includes scheduled monitoring, as well as therapies to eliminate excess Ca, maintain hydration, and prevent loss of bone mass. Scheduled monitoring should include biannual serum Ca measurement, annual assessment for overt signs or symptoms of hyperparathyroidism, serum creatinine measurement, and BMD testing.16
Surgical Treatment
Surgery is the only known cure for PHPT. Four consensus meetings to address the surgical management of asymptomatic PHPT have been held, with the most recent workshop in 2013 (see Table 2). The guidelines recommend surgery for patients with biochemically confirmed PHPT and overt signs and symptoms. Parathyroid surgery is also recommended for asymptomatic individuals who meet specific laboratory or radiology thresholds.20 Even when there is no specific indication for surgery, parathyroidectomy
Implications for Primary Care NPs
For patients who are not candidates for parathyroidectomy, primary care providers can recommend supportive preventive measures with appropriate monitoring.7 Patient education should include medication reconciliation, avoidance of volume depletion, and education regarding Ca intake. Physical activity prevents bone resorption, and 400-600 IU of vitamin D daily may prevent PTH secretion and bone resorption. Nephrolithiasis may be minimized by adequate water intake. Bisphosphonates, calcimimetics,
Conclusions
The evaluation and medical management of patients with hypercalcemia is challenging. Mild or less-than-obvious symptoms of PHPT can delay diagnosis and treatment. Once the diagnosis is confirmed, surgery improves quality of life and bone health. The current surgical guidelines should be applied early in the disease process to prevent progression of the disease, even in those patients who continue to be normocalcemic.11 Consideration of PHPT is essential in the differential diagnosis of patients
Roseann Velez, DNP, FNP, is an instructor at Johns Hopkins University School of Nursing and practices at Greater Baltimore Medical Associates in Hunt Valley, MD. She can be reached at [email protected].
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Roseann Velez, DNP, FNP, is an instructor at Johns Hopkins University School of Nursing and practices at Greater Baltimore Medical Associates in Hunt Valley, MD. She can be reached at [email protected].
Mary Donnelly-Strozzo, DNP, ANP-BC, is an instructor at Johns Hopkins University School of Nursing and Site Supervisor Wald Community Nursing Center.
Julie Stanik–Hutt PhD, GNP/ACNP-BC, is a professor at the University of Iowa College of Nursing.
In compliance with national ethical guidelines, the authors report no relationships with business or industry that would pose a conflict of interest.
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American Association of Nurse Practitioners (AANP) members may receive 1.0 continuing education contact hours, approved by AANP, by reading this article and completing the online posttest and evaluation at cecenter.aanp.org/program?area=JNP.