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Questions and Answers
What is the primary function of parathyroid hormone (PTH) in the body?
What is the primary function of parathyroid hormone (PTH) in the body?
What is the most common cause of primary hyperparathyroidism?
What is the most common cause of primary hyperparathyroidism?
Which of the following laboratory findings would most likely be present in secondary hyperparathyroidism?
Which of the following laboratory findings would most likely be present in secondary hyperparathyroidism?
Which condition can lead to osteitis fibrosa cystica?
Which condition can lead to osteitis fibrosa cystica?
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What common laboratory finding would you expect in a patient with hypoparathyroidism?
What common laboratory finding would you expect in a patient with hypoparathyroidism?
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What symptom is commonly associated with low serum calcium in hypoparathyroidism?
What symptom is commonly associated with low serum calcium in hypoparathyroidism?
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Which of the following is a typical consequence of elevated PTH levels on bone health?
Which of the following is a typical consequence of elevated PTH levels on bone health?
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In secondary hyperparathyroidism, what triggers the excessive secretion of PTH?
In secondary hyperparathyroidism, what triggers the excessive secretion of PTH?
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Study Notes
Parathyroid Glands - Basic Principles
- Chief cells control serum calcium levels via parathyroid hormone (PTH) secretion.
- PTH increases bone resorption, releasing calcium and phosphate.
- PTH increases calcium absorption in the small intestine (indirectly via vitamin D).
- PTH increases calcium reabsorption in the kidneys, and decreases phosphate reabsorption.
- Increased ionized calcium in the blood negatively feeds back to decrease PTH secretion.
Primary Hyperparathyroidism
- Excess PTH due to a disorder of the parathyroid gland itself.
- Most common cause is a parathyroid adenoma (over 80% of cases).
- Parathyroid hyperplasia and carcinoma are less common.
- Adenoma is usually a single gland benign tumor.
- Often asymptomatic hypercalcemia.
- Potential consequences include kidney stones (nephrolithiasis), kidney damage (nephrocalcinosis), nervous system issues (e.g., depression, seizures), constipation, peptic ulcers, and pancreatitis.
- Osteitis Fibrosa Cystica is a bone resorption condition.
- Diagnostic tests reveal elevated PTH, calcium, and urine cAMP, along with elevated alkaline phosphatase.
- Treatment typically involves surgical removal of the affected gland.
Secondary Hyperparathyroidism
- Excess PTH due to a disease process outside the parathyroid gland.
- Chronic kidney failure is the most common cause.
- Renal insufficiency leads to decreased phosphate excretion.
- Increased serum phosphate binds free calcium.
- Low calcium stimulates all four parathyroid glands.
- PTH increases bone resorption, contributing to renal osteodystrophy.
- This condition leads to elevated PTH, decreased calcium, elevated phosphate, and elevated alkaline phosphatase.
Hypoparathyroidism
- Low PTH levels.
- Can result from autoimmune damage, surgical removal, or DiGeorge syndrome.
- Symptoms include numbness, tingling (especially around the mouth), muscle spasms (tetany), triggered by a blood pressure cuff (Trousseau sign) or tapping on the facial nerve (Chvostek sign).
- Diagnostic tests show decreased PTH and calcium.
- Pseudohypoparathyroidism is due to end-organ resistance to PTH, and shows hypocalcemia with increased PTH levels.
- Autosomal dominant form is linked to short stature and short 4th and 5th digits.
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Description
This quiz explores the fundamental concepts of parathyroid glands and their function in regulating calcium levels in the body. It also delves into primary hyperparathyroidism, its causes, symptoms, and potential complications. Test your understanding of PTH mechanisms and related health issues!
