All are true about hyperparathyroidism except?
**Core Concept**
Hyperparathyroidism is a condition characterized by the excessive production of parathyroid hormone (PTH) by one or more parathyroid glands. This leads to an increase in serum calcium levels due to increased bone resorption, increased renal calcium reabsorption, and increased intestinal calcium absorption.
**Why the Correct Answer is Right**
Hyperparathyroidism can cause a variety of clinical manifestations, including hypercalcemia, kidney stones, bone resorption, and neuropsychiatric symptoms. The increased PTH levels lead to the activation of osteoclasts, which resorb bone, releasing calcium into the bloodstream. Additionally, PTH promotes renal calcium reabsorption and intestinal calcium absorption, further contributing to hypercalcemia.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hyperparathyroidism typically presents with hypercalcemia, not hypocalcemia.
**Option B:** This option is incorrect because hyperparathyroidism is associated with increased bone resorption, not increased bone density.
**Option C:** This option is incorrect because while vitamin D deficiency can contribute to hyperparathyroidism, it is not a direct cause of the condition.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of hyperparathyroidism is the presence of kidney stones, which are a common complication of the condition. This is due to the increased calcium levels in the urine, which can lead to the formation of calcium oxalate stones.
**Correct Answer:** A. Hyperparathyroidism typically presents with hypercalcemia, not hypocalcemia.