Renal failure is by far the most common cause of secondary hyperparathyroidism**.** If kidneys are unable to convert vitamin D to its active form, serum vitamin D levels will drop. Lower vitamin D levels reduce the absorption of calcium in the intestines and reduce the kidneys' ability to resorb calcium from the urine. In addition, if the kidneys are unable to adequately excrete phosphate, calcium phosphate forms, which further lowers free calcium levels in the blood. Poor nutrition is not a common cause of secondary hyperparathyroidism, though low vitamin D levels due to malabsorption can be a contributing factor. Pituitary tumors can be seen with hyperparathyroidism when part of multiple endocrine neoplasia type I, but this is not as common as renal failure. Bone cancers are more often associated with elevated calcium levels, resulting in low or undetectable parathyroid hormone levels.

The correct answer is "to prevent lactic acidosis while hospitalized." This is the correct answer because a known side effect of metformin use is development of lactic acidosis (a form of metabolic acidosis). Patients who are hospitalized, especially if hospitalized for infections, like pneumonia, are independently at an elevated risk of developing a lactic acidosis. As such, to minimize the risk of lactic acidosis, a modifiable risk factor, metformin use, is frequently temporarily discontinued while inpatient. Patients on metformin are frequently switched to sliding-scale insulin as inpatients, as this allows for adequate glycemic monitoring, titration, and control. Once they are stable for discharge and the cause of their hospitalization is addressed and treated, most can be safely discharged home on metformin without issue.

While numerous measures are carried out while patients are hospitalized to prevent myocardial infarction, stroke, headache, and depression, the switching of metformin to sliding-scale insulin is not performed specifically for any of those reasons.

The correct answer is prednisone. Of all the medications listed, prednisone is the only medication that is known to cause hyperglycemia.

Prednisone has a number of side effects including hyperglycemia, acne, headache, restlessness, insomnia, nausea, vomiting, and weight gain, among others.

Clindamycin's side effects include diarrhea (including Clostridium difficile), and less commonly nausea, vomiting, and abdominal pain, among others, but not hyperglycemia.

Ketorolac's side effects include renal toxicity, tinnitus, heartburn, diarrhea, and abdominal pain, among others, but not hyperglycemia.

Lisinopril's side effects include hypotension, lightheadedness, angioedema, and barky cough, among others, but not hyperglycemia.

Simvastatin's side effects include muscle pains/aches, muscle weakness, and less frequently confusion, and electrolyte disturbances, but not hyperglycemia.

Conn syndrome (primary hyperaldosteronism) is hypertension due to elevated levels of aldosterone. High aldosterone causes excretion of potassium and retention of sodium, which leads to water retention and increase in blood pressure. While elevated levels of vasopressin (antidiuretic hormone) would also cause hypertension, Conn syndrome refers to the hypersecretion of aldosterone.

80% of cases of Cushing's disease are caused by adrenocorticotropic hormone (ACTH)-secreting adenomas of the anterior pituitary. High ACTH ends up causes adrenal hyperplasia, which leads to secretion of extra cortisol. Corticosteroid use is the leading cause of Cushing syndrome, rather than Cushing's disease.

Insulin activates sodium-potassium ATPase in skeletal muscle cells causing an influx of potassium. Under certain circumstances, an incorrectly administered injection of insulin may kill patients due to its ability to acutely suppress plasma potassium concentrations.

Smokers have higher levels of the chemical thiocyanate, a degradation product of cyanide in tobacco smoke, which can block iodine uptake by the thyroid. A high oxalate diet is associated with kidney stones, asbestos exposure is associated with mesothelioma, and nonsteroidal anti-inflammatory drugs (NSAIDs) use, while associated with several gastric disorders, has not been shown to have a significant effect on thyroid function.

GLUT-2 is the primary carrier for glucose transport into pancreatic beta cells. It does not depend on insulin to function. It thus aids the pancreatic beta cells sense glucose levels in the blood, which are then triggered to release insulin. GLUT-4 is active primarily in adipose and muscle tissue.

Hypothyroidism usually involves weight gain so a lower calorie diet with frequent small meals are recommended. High fiber, low calorie diets and stool softeners will help to alleviate these symptoms. Antiglycemics and hemoglobin A1C tests are indicated for diabetics.

Tetany is a complication due to hypocalcemia which can occur if the parathyroid glands which control calcium balance are accidentaly injured during thyroidectomy. Tetany is associated with nerve excitability and sustained muscle contractions, or spasms. Tetanus, bone pain, and oliguria are not associated with complications of a thyroidectomy. Goiter is a manifestation of an overactive thyroid.