Susan, a 60-year-old woman with a history of chronic kidney disease (CKD) stage 4, presented to the nephrology clinic complaining of bone pain and muscle weakness. Laboratory investigations revealed elevated serum phosphate levels and a persistently low serum calcium level. Her intact parathyroid hormone (PTH) levels were markedly elevated. Susan's radiographic findings showed diffuse demineralization of bones on X-ray and a DEXA scan confirmed the presence of severe osteoporosis. This would be an example of:

John, a 55-year-old male, presented to the endocrinology clinic with a six-month history of increasing fatigue, generalized bone pain, and recurrent kidney stones. On examination, he displayed signs of mild dehydration and muscle weakness. Laboratory tests revealed elevated serum calcium levels, with a concomitant inappropriately normal or elevated parathyroid hormone (PTH) level. A neck ultrasound showed a suspicious parathyroid adenoma. This would be a case of:

A patient presents to clinic with symptoms of tetany, carpopedal spasm, hyperreflexia, positive Chvostek sign, positive Trousseau sign, and a long QT interval on EKG. What type of parathyroid condition would result in these symptoms?

James, a 45-year-old man, presented to the endocrinology clinic with a three-month history of persistent headaches, muscle weakness, and intermittent episodes of palpitations. Clinical examination revealed hypertension, and further investigation demonstrated hypokalemia and metabolic alkalosis. Laboratory tests revealed elevated levels of plasma aldosterone, suppressed plasma renin activity, and an increased aldosterone-to-renin ratio. A contrast-enhanced abdominal CT scan showed an adenoma in the left adrenal gland. What is James' diagnosis?

Emma, a 30-year-old woman, was admitted to the internal medicine ward with a two-month history of progressive weakness, fatigue, and unintentional weight loss. She reported hyperpigmentation of her skin and episodes of dizziness upon standing. On examination, her blood pressure was significantly lower than expected, and she exhibited generalized hyperpigmentation. Laboratory tests revealed hyponatremia, hyperkalemia, and a markedly elevated plasma adrenocorticotropic hormone (ACTH) level. Further testing confirmed low levels of serum cortisol. An adrenocortical antibody test was positive. What is this patient's diagnosis?

In Addison's disease, low cortisol levels result in positive feedback, elevating which of the following lab values?

Sophia, a 38-year-old woman, presented to the endocrinology clinic with a myriad of symptoms that had been progressively worsening over the past year. She reported weight gain, particularly around the central abdomen, easy bruising, facial rounding, muscle weakness, and abnormal menstruation. Additionally, Px reports that her skin has become darker than normal as well as excessive hair growth on her upper lip, chin, and sideburns. On examination, she displayed classic features of Cushing's, including moon facies, buffalo hump, and purple striae on her abdomen. Laboratory tests revealed elevated levels of cortisol in both the morning and evening, with a lack of the normal diurnal cortisol rhythm. This patient's condition arises at the level of the:

Cushing's disease arises at the level of the ___ whereas Cushing's syndrome arises at the level of the ___.

What values are elevated in Cushing's disease? Select all that apply:

Mark, a 45-year-old man, sought medical attention due to recurrent episodes of severe headaches, sweating, and palpitations that occurred unpredictably over the past six months. During one of these episodes, his blood pressure was found to be significantly elevated. Mark's primary care physician referred him to the endocrinology clinic suspecting a possible adrenal disorder. What lab values and tests would help to confirm a diagnosis of pheochromocytoma?