Summary
Overview
Dr. Sargent Zach Vigeese, a consultant in diabetes, endocrinology, and general internal medicine, shares her extensive knowledge and passion for calcium metabolism, parathyroid function, and bone health. The discussion explores how parathyroid hormone fiercely defends calcium levels, the evolutionary origins of these systems dating back 375 million years, and practical guidance on osteoporosis prevention and treatment. The conversation reveals fascinating connections between ancient fish gills, space travel, hibernating bears, and modern bone health management.
The Parathyroid Gland: Discovery and Function
The parathyroid glands, four pea-shaped structures sitting behind the butterfly-shaped thyroid, were first discovered in an Indian rhinoceros from London Zoo in the 1880s. These glands produce parathyroid hormone, which fiercely defends calcium levels in the blood by releasing calcium from bones when levels drop. The hormone works continuously to maintain calcium for critical functions like nerve conduction and muscle contraction, even at the expense of bone density.
- Parathyroid glands are four pea-shaped glands behind the thyroid that regulate calcium levels
- The glands were discovered from an Indian rhinoceros at London Zoo and initially called the 'glands of Owen'
- Parathyroid hormone releases calcium from bone when blood calcium drops, using osteoclasts to break down bone
- Low calcium episodes cause the parathyroid glands to grow bigger over time through a ratcheting mechanism that never reverses
" The parathyroid gland was named by a medical student in Sweden in the 1880s when he was cataloguing specimens. They were discovered from an Indian rhinoceros from London Zoo. "
" Your bones will be sacrificed in order that your nerves can conduct and your muscles can contract. "
Parathyroid Disorders: Too Much and Too Little
Hyperparathyroidism occurs when parathyroid glands produce too much hormone, leading to calcium being pulled from bones and creating osteoporosis, while excess calcium filtered by the kidneys causes kidney stones. Hypoparathyroidism is less common, usually resulting from thyroid surgery when parathyroid glands are accidentally removed. Treatment for hypoparathyroidism requires both calcium and activated vitamin D, since parathyroid hormone is needed for the final activation step of vitamin D in the kidneys.
- Hyperparathyroidism causes thin bones (osteoporosis) and kidney stones from excess calcium being washed through the kidneys
- Hypoparathyroidism most commonly occurs after thyroidectomy when parathyroid glands are accidentally removed
- Without parathyroid hormone, the body cannot complete the final activation of vitamin D in the kidneys
- People with kidney failure or missing parathyroid glands need activated vitamin D supplements
" You can think of the kidneys as like the washing machines of the body. So the kidneys having to wash all this blood. If there's too much calcium, you get Lyme scales, you get kidney stones. "
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