Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ KEY FEATURES +++ ESSENTIALS OF DIAGNOSIS ++ Inappropriately normal or elevated parathyroid hormone (PTH) levels Serum calcium level above upper limit of normal (> 10 mg/dL) corrected for serum albumin, or ionized calcium level higher than upper limit of normal range Increased 24-hour urine calcium excretion (> 200 mg) Elevated alkaline phosphatase Decreased serum phosphate level Elevated serum calcium due to parathyroid hormone excess +++ GENERAL CONSIDERATIONS ++ PTH mainly regulates ionized calcium levels in the blood by interacting with bone, intestinal mucosa, and the kidney. PTH has few direct effects on the heart but can affect the cardiovascular system through its regulation of calcium The most common cause of hyperparathyroidism is overproduction of PTH from a parathyroid adenoma Secondary hyperparathyroidism is seen with chronic hypocalcemia, vitamin D deficiency, or renal failure Tertiary hyperparathyroidism occurs when secondary hyperparathyroidism becomes autonomous, as in renal failure Rarely, PTH overproduction can occur with parathyroid hyperplasia as part of multiple endocrine neoplasms Secondary causes of hypercalcemia must be excluded such as granulomatous disease, excess calcium ingestion, vitamin D and A toxicity, thyrotoxicosis, adrenal insufficiency, and malignancies Increased calcium can adversely affect the cardiovascular system and lead to hypertension, arrhythmias, and calcification of heart and vascular structures +++ CLINICAL PRESENTATION +++ SYMPTOMS AND SIGNS ++ Most patients are asymptomatic Some patients report a variety of nonspecific symptoms +++ PHYSICAL EXAM FINDINGS ++ Calcium deposits in the cornea, soft tissue, and joints Signs of left ventricular hypertrophy or valve sclerosis Bradycardia and hypertension may occur with acute hypercalcemia +++ DIFFERENTIAL DIAGNOSIS ++ Other causes of hypercalcemia without PTH excess Valvular sclerosis from other causes Other causes of hypertension and left ventricular hypertrophy +++ DIAGNOSTIC EVALUATION +++ LABORATORY TESTS ++ Elevated serum calcium and ionized calcium Inappropriately normal or high PTH level Other causes of high calcium are associated with low PTH levels Low serum phosphate levels Hyperchloremic metabolic acidosis, elevated serum chloride, reduced carbon dioxide Elevated alkaline phosphatase levels, especially with hyperparathyroid bone disease +++ ELECTROCARDIOGRAPHY ++ Shortened ST segment and decreased QT interval With serum calcium levels > 16 mg/dL, the T wave widens, prolonging the QT interval +++ IMAGING STUDIES ++ Echocardiography: shows left ventricular hypertrophy and calcification of the aortic root and aortic and mitral valves Chest x-ray: calcification of the coronary arteries and aorta +++ TREATMENT +++ CARDIOLOGY REFERRAL ++ Suspected cardiac disease +++ HOSPITALIZATION CRITERIA ++ Planned surgery +++ MEDICATIONS ++ Pharmacologic treatment with bisphosphonates, pamidronate, risedronate, cinacalcet, and high-dose estrogen in postmenopausal women is less effective than surgery Acute hypercalcemia ... Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.