NYACP Board Review Question of the Week
Every other Tuesday, NYACP members are sent a Board Review Question from ACP's MKSAP 18 to test professional knowledge and help prepare for the exam. Participant totals and answer percentages are distributed on the first Thursday of the month in IM Connected, the Chapter's eNewsletter, and are also published on this page.
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March 25, 2025
MKSAP 19 Endocrinology & Metabolism, Question 46
A 70-year-old woman is evaluated for incidentally discovered hypercalcemia. She has no symptoms or other medical conditions and takes no medications.
On physical examination, vital signs are normal. A height loss of 5 cm (2.0 inches) has occurred since age 65 years. Thoracic kyphosis is noted.
Kidney-urinary-bladder radiograph is negative for kidney stones. Dual-energy x-ray absorptiometry scan shows femur neck T-score of -1.9, lumbar spine T-score -1.8, and distal one-third radius T-score of -1.7.
Which of the following is the most appropriate management?
A. Order parathyroid sestamibi scan
B. Order thoracic and lumbar spine radiography
C. Repeat serum calcium and creatinine measurement in 6 months
D. Start alendronate
Responses Received from Members (Graph is uploaded on Thursday afternoon):
The Correct Answer is: B. Order thoracic and lumbar spine radiography
Educational Objective:
Manage asymptomatic primary hyperparathyroidism.
The most appropriate management for this patient is thoracic and lumbar spine radiography (Option B). This patient has hypercalcemia, hypophosphatemia, and an inappropriately elevated serum parathyroid hormone level, establishing the diagnosis of primary hyperparathyroidism. For asymptomatic patients with primary hyperparathyroidism, additional evaluation is necessary to determine if parathyroidectomy is indicated. Evaluation in most patients includes assessment of kidney function, bone mineral density (BMD) measurement, and in some patients, assessment for nephrolithiasis or nephrocalcinosis. In addition to evidence of bone disease, indications for parathyroidectomy in patients with primary hyperparathyroidism include age younger than 50 years; serum calcium 1 mg/dL (0.3 mmol/L) or greater above upper limit of normal; creatinine clearance less than 60 mL/min; 24-hour urine calcium greater than 400 mg/dL (100 mmol/L); or nephrolithiasis or increased risk for kidney stones. This patient's evaluation is nearly complete except for evaluation for vertebral fractures. Because this patient's height loss and kyphosis suggest the possibility of vertebral fractures, she should undergo thoracic and lumbar spine radiography; the presence of vertebral fractures would be an indication for parathyroidectomy.
A parathyroid sestamibi scan (Option A) or neck ultrasonography may be appropriate for preoperative adenoma localization if surgery is indicated. Localization studies, however, do not influence the choice between surgical and medical management of primary hyperparathyroidism.
Patients without indications for parathyroidectomy require periodic reassessment that includes repeat serum calcium and creatinine measurement (Option C) every 6 to 12 months and BMD measurement of the lumbar spine, hip, and distal radius every 2 years. This patient requires further assessment for the presence of vertebral fractures before deciding on a monitoring strategy versus parathyroidectomy.
Although alendronate (Option D) suppresses bone resorption and improves BMD at the lumbar spine in patients with primary hyperparathyroidism, it has not been shown to reduce fracture risk, serum calcium levels, or urine calcium levels in these patients. Patients at high risk for fracture (T-score <-2.5 at lumbar spine, total hip, femoral neck, or distal one-third radius and/or prevalent fragility fracture) at presentation or during monitoring should undergo parathyroidectomy. Alendronate would be an appropriate option for a patient with primary hyperparathyroidism and concurrent osteoporosis who was unable or unwilling to undergo surgery.
Key Point
In patients with primary hyperparathyroidism, bone-related indications for parathyroidectomy include fragility fractures, vertebral fractures, and a dual-energy x-ray absorptiometry T-score of less than -2.5 or less at lumbar spine, total hip, femoral neck, or distal one-third radius.
Bibliography
Insogna KL. Primary hyperparathyroidism. N Engl J Med. 2018;379:1050-1059. PMID: 30207907 doi:10.1056/NEJMcp1714213
Copyright 2019, American College of Physicians.
March 11, 2025
MKSAP 18 Endocrinology & Metabolism, Question 50
A 45-year-old woman comes to the office to review her thyroid function test results. Thyroid function testing was ordered in response to a recent diagnosis of hypercholesterolemia. The patient is otherwise well, and she takes no medications.
On physical examination, vital signs are normal. Her physical examination is normal with the exception of slowed relaxation phase of deep tendon reflexes.
Laboratory studies show a serum thyroid-stimulating hormone (TSH) level of 24 µU/mL (24 mU/L) and a free thyroxine (T4) level of 0.65 ng/dL (8.4 pmol/L).
Which of the following is the most appropriate treatment?
A. Desiccated thyroid extract
B. Low-dose (25-µg) levothyroxine
C. Weight-based replacement dose of levothyroxine
D. No treatment
Responses Received from Members (917 Responses):
The Correct Answer is: C. Weight-based replacement dose of levothyroxine
Educational Objective:
Treat hypothyroidism with weight-based dosing of levothyroxine.
This patient has hypothyroidism, and the most appropriate treatment is to prescribe a weight-based replacement dose of levothyroxine (1.6 µg/kg lean body weight). For patients with high body mass index values, an estimate of lean mass should be determined. Levothyroxine is the treatment of choice for thyroid hormone deficiency. Goals of therapy are to resolve signs and symptoms of hypothyroidism, normalize serum thyroid-stimulating hormone (TSH), and avoid overtreatment.
Although some patients express a preference for treatment with desiccated thyroid hormone (thyroid extract), there are potential safety concerns and lack of data on long-term outcomes. The physiologic ratio of thyroxine (T4) to triiodothyronine (T3) secreted by the human thyroid is approximately 15:1, whereas desiccated thyroid hormone, as originally derived from animal thyroid glands, contains supraphysiologic T3 (T4 to T3 ratio 4:1). Patients taking desiccated thyroid hormone frequently experience low serum T4 and supraphysiologic T3 levels despite having a serum TSH within the reference range.
Although a full replacement dose of levothyroxine can be administered to most patients with overt hypothyroidism, older adults (age 65 years and older) and patients with cardiovascular disease should be prescribed a lower initial dose (25-50 µg/day) due to the effects of thyroid hormone on myocardial oxygen demand. The dose should be titrated based on TSH levels measured 6 to 8 weeks after any dose change. The patient described here is an otherwise healthy woman in her fifth decade of life.
Prescribing a low initial dose of levothyroxine would unnecessarily delay correction of hypothyroidism.
Not prescribing treatment is also inappropriate. Although the patient does not currently report symptoms of thyroid hormone deficiency, she has overt hypothyroidism with physical findings consistent with this diagnosis (slowed reflexes) and evidence of metabolic complications (hypercholesterolemia). Hypothyroidism causes hypercholesterolemia through reduced cholesterol metabolism and contributes to the development of cardiovascular disease. Treatment of patients with overt hypothyroidism is indicated to ameliorate the risk of these complications. Guidelines differ regarding when to treat subclinical hypothyroidism (elevated serum TSH level with free T4 or total T4 levels within the reference range). For most adults with subclinical hypothyroidism, thyroid hormone replacement will result in no clinical benefits and may have little or no effect on cardiovascular events or mortality. However, treatment should be provided to women who are trying to become pregnant or patients with TSH levels greater than 20 µU/mL (20 mU/L), and treatment may be reasonable for patients with severe symptoms or adults aged 30 years old or younger.
Key Point
Levothyroxine is the treatment of choice for thyroid hormone deficiency; for most younger adults without cardiac disease, a weight-based replacement dose of levothyroxine (1.6 µg/kg lean body weight) is recommended.
Bibliography
Hennessey JV. The emergence of levothyroxine as a treatment for hypothyroidism. Endocrine. 2017;55:6-18. PMID: 27981511 doi:10.1007/s12020-016-1199-8
Copyright 2018, American College of Physicians.