Endocrinology Flashcards
General Principals
What does dopamine inhibit? (2)
TSH and prolactin
General Principals
What does somatostatin inhibit? (2)
TSH and GH
General Principals
TRH stimulates what two things?
TSH and prolactin
General Principals
What lab abnormalities are seen in patients with increased aldosterone levels? (3)
Hypokalemia
Metabolic alkalosis
Hypernatremia - Volume Expansion
Calcium and Bone Disorders
MEN 1
3 Ps
Parathyroid adenoma/hyperplasia
Pancreatic tumors
Pituitary adenoma
Calcium and Bone Disorders
MEN 2A?
2P - Pheochromocytoma/Parathyroid adenoma/Medullary thyroid cancer
Calcium and Bone Disorders
Men 2B?
1P
Pheochromocytoma
Marnoid body habitus/Mucosal neuromas
Medullary thyroid cancer
Calcium and Bone Disorders
What do MEN 2a and 2b have in common?
Both have pheochromocytoma and medullary thyroid cancer
Calcium and Bone Disorders
HCTZ causes what in terms of hypercalcemia?
High normal or modestly elevated calcium levels
Calcium and Bone Disorders
Describe pathogenesis of secondary hyperparathyroidism?
Secondary hyperparathyroidism is from ESRD/CKD which causes an increase in serum phosphorus and decreased calcium (calcium level can also be normal). This triggers increased PTH secretion (becomes a feedback loop)
Calcium and Bone Disorders
Describe treatment guidelines in secondary hyperparathyroidism in relation to phosphorous?
Hyperphosphatemia - dietary phosphorus restriction (< 900 mg/day). If phosphorus is still elevated, use non-calcium containing phosphorus binders (sevelamer).
Calcium and Bone Disorders
Describe treatment guidelines in secondary hyperparathyroidism in relation to Calcium?
Don’t treat with calcium replacement if serum calcium > 7.5. Overtreatment may cause vascular calcification with calciphylaxis.
Calcium and Bone Disorders
Describe treatment guidelines in secondary hyperparthyroidism in relation to PTH?
If serum PTH > 300, use vitamin D analogs like calcitriol or calcimimetic (cinacalcet)
Calcium and Bone Disorders
Name of Active Form of Vitamin D
Active Form of Vitamin D = 1,25-OH-Vitamin-D = Calcitriol
Calcium and Bone Disorders
Three functions of Active Form of Vitamin D
Calcitriol (1,25-OH-Vit-D) functions:
1. Decrease PTH
2. Increase Calcium
3. Increase Phosphorous
Calcium and Bone Disorders
How is vitamin D processed by the body?
Vitamin D is observed via diet or sunlight. It goes to the liver where it is hydroxylated to form 25-OH-Vitamin-D. It goes to the kidneys where it is hydroxylated to form active vitamin D, aka calcitriol aka 1,25-OH-Vit-D.
Calcium and Bone Disorders
Three function of PTH?
- Increase Calcium
- Decrease Phosphorous
- Increase 1,25-OH-Vitamin-D via acting on the kidneys
Obesity
What is normal BMI?
What is BMI cutoff for Obesity?
Normal BMI = 18.5-24.9
BMI cutoff for obesity = > 30
Obesity
When is bariatric surgery considered for obesity patients? (2)
- Patients with a BMI > 40
- Patients with a BMI > 35 with > 1 severe weight related diseases/complications who have not met weight-loss goals with exercise, diet, and medications
Calcium and Bone Disorders
What does Calcitonin do? (2)
What stimulates production of Calcitonin?
PTH antagonist
1. Slows down bone resorption
2. Increases calciuria
Calcitonin is increased when there is hypercalciemia present.
Calcium and Bone Disorders
Causes of hyperparathyroidism? (3)
- Solitary adenomas of parathyroid glands (80% of causes)
- Hyperplasia of all four parathyroid glands
- Carcinoma of the parathyroid gland
Calcium and Bone Disorders
Symptoms of Hypercalcemia
Bones, Stones, Abdominal Moans, and Psychic Groans
- Bones - increased risk of fractures, bone aches, and pain
- Stones - increased risk of calcium containing kidney stones
- Abdominal moans - constipation, nausea, anorexia, abdodminal pain
- Psychic groans - confusion, memory loss, and delirium
Other symptoms - **polyuria, polydipsia, shortened QT interval **
Calcium and Bone Disorders
Causes of increased PTH/normal PTH and hypercalcemia? (3)
AKA PTH dependent hypercalcemia
- Primary hyperparathyroidism
- Familal hypocalciuric hypercalcemia
- Lithium
Calcium and Bone Disorders
Can a patient with primary hyperparathyroidism have a normal PTH?
Yes, patients with a normal intact PTH with an elevated calcium level is still comptabile with the diagnosis of hyperparathyroidism
Calcium and Bone Disorders
What are next steps in patients with hypercalcemia and high or normal PTH?
Measure 24-hour urinary calcium and creatinine excretion. Urinary calcium excretion is low in familal hypocalciuric hypercalcemia but normal to high in primary hyperparathyroidism.
Calcium and Bone Disorders
Treatment of Hypercalcemia
- Aggressive volume resuscitation with normal saline (3-4L of NS)
- Calcitonin will take effect rapidly but action is short lived (tachyphylaxis).
- Only use loop diuretics if patient develops volume overload from saline resuscitation
- Bisphosphonates - take effect over several days. Paamidronate and zoledronic acid take effect in 48 hours.
Glucocorticoids if concerned about sarcoidosis or other granulomatous disorders
**Discontinue thiazide diuretics **
Calcium and bone disorders
Side effect of bisphonate therapy?
- Osteonecrosis of the jaw
Calcium and Bone disorders
Next step once primary hyperaparathyroidism is confirmed?
Perform US or sestambi scans to localize possible parathyroid adenoma causing hyperparathyroidism
Calcium and Bone disorders
What is a treatment option for paitents with patients with primary hyperparathyroidism who are not surgical candidates for surgical parathyroidectomy?
Cinacalet
Calcium and Bone Disorders
What are some causes of hypercalcemia with decreased PTH levels? (7)
- Immoblization
- Excess Vitamin D
- Excess Vitamin A
- Granuloamatous disease (Sarcoid/TB)
- Thyrotoxicosis
- Milk Alkalli syndrome
- Malignancy
Calcium and Bone Disorders
What are the mechanisms of hypercalcemia of malignancy (3)
- Osteolytic bone lesions
- PTHrP production
- Extra-renal 1-alpha-hydroxylase production to make 1,25-OH-Vit D (Lymphoma)
Bone and Calcium Disorders
Describe Milk-Alkali syndrome features (3)
What causes Milk-Alkali syndrome
Milk-Alkali syndrome is characterized by hypercalcemia, renal insufficiency, and metabolic alkalosis (alkali).
Caused by excessive ingestion of calcium carbonate.
Calcium and Bone Disorders
When should patients with hypercalcemia from primary hyperparathyroidism have surgical parathyroidectomy?
When symptomatic from hyperparathyroidism.
Symptoms can include low bone desensity, kidney stones, CKD
Calcium and Bone Disorders
What are some symptoms of hypocalcemia?
- Can have nonspecific symptoms like weakness, anxiety, depression
- Oral Parethesias
- Tetany
- Chvostek sign (spasm of the facial nerve when tapped)
- Trousseau sign (carpopedal spasm elicited by inflation of the blood pressure cuff above systolic pressure)
- Prolonged QT on EKG
- Bronchospasm
Calcium and Bone Disorders
Severe Hypocalcemia can cause ________. ________ is a metabolic derangement that exacerbates hypocalcemic ________. ____ is a metabolic derangement that is protective agianst ________.
Severe hypocalcemia can result in seizures. Alkalosis is a metabolic derangement that can exacerbate hypocalcemic seizures. Acidosis is a metabolic derangement that is protective against hypolcemic seizures.
Calcium and Bone Disorders
Describe hungry bone syndrome pathogenesis and when it is seen?
Hungry bone syndrome is seen in patients after parathyroidectomy. *PTH causes a net efflux of calcium from bones. Acute withdrawal of PTH causes a net influx of calcium onto bone. *
Risk factors for hungry bone syndrome include moderate to severe hyperparathyroidism before surgery with evidence of high bone turnover (elevated ALK-P).
PTH levels are usually normal but can be elevated. Phosphate and magnesium are also resorbed onto bone with calcium resulting in hypomagnesemia, hypophosphatemia, and hypocalcemia.
Calcium and Bone Disorders
What electrolyte deficiency can worsen hypocalcemia? What types of patients is severe deficiency of this electrolyte seen in?
Severe hypomagnesemia can worsen hypocalcemia. Seen in alcoholics and patients with bowel disease (prevents absorption of magnesium)
Calcium and Bone Disorders
Describe how celiac disease can result in hypocalcemia?
Uncontrolled celiac disease results in decreased gastrointestinal vitamin D absorption and subsequent vitamin D deficiency.
This leads to hypocalcemia (and hypophophastemia) and causes PTH to rise.
Increased PTH leads to normal calcium levels, low phosphorous, high PTH, and elevated Alkaline phosphatase (from increased bone turnover).
Calcium and Bone Disorders
What is osteomalacia? How does it present in adults? What is a common cause of osteomalacia?
Osteomalacia is undermineralized bone. In adults, it presents with signs of bone pain. Commonly caused by vitamin D deficiency.
Calcium and bone disorders
Lab finding in Osteomalacia (2)?
Hypocalcemia
Elevated alkaline phosphatase
Calcium and Bone Disorders
MEN genetics?
All are autosomal dominant with varying expression.
Calcium and Bone Disorders
Most common pituitary tumor and pancreatic tumor in MEN1?
Pancreatic tumor - Gastrinoma (causes PUD). Other pancreatic tumors include glucagonoma, insulinoma, VIPoma
Pituitary tumor - Prolactinoma
Calcium and Bone Disorders
Symptoms of glucononoma? (3)
- Mild hyperglycemia
- Glossitis with a beefy red tongue
- Migratory necrolytic erythema - blistering erythemaatous rash found in the groin region
Calcium and Bone Disorder
Key lab finding in medullary thyroid cancer?
High calcitonin levels
General Principals
How does the hypothalamus control the anterior pituitary and the posterior pituitary?
Hypothalamus exerts control over the posterior pitutiary by direct nerve stimulation. Hypothalamus exerts control over the anterior pitutiary by releasing hormones.
