Parathyroid disorders and calcium Flashcards
What is the parathyroid gland?
The parathyroid gland is a small endocrine gland located in the neck, typically consisting of four small pea-sized glands, responsible for regulating the body’s calcium and phosphorus levels.
How is parathyroid hormone (PTH) physiologically produced?
When calcium levels in the blood are low, the parathyroid glands release PTH into the bloodstream which stimulates the kidneys to produce an active form of vitamin D known as calcitriol. Calcitriol increases calcium absorption in the intestines, which helps to raise blood calcium levels and suppress PTH release.
function of PTH
stimulates the release of calcium from bones
increases calcium absorption in the intestines
decreases calcium excretion in the kidneys
PTH also increases the excretion of phosphorus in the urine, which helps to maintain a balance between calcium and phosphorus levels in the body.
hyperparathyroidism causes what
high levels of calcium in the blood.
primary and secondary
causes of primary hyperparathyroidism
benign tumour on one of the parathyroid glands, and hyperplasia of the parathyroid glands.
causes of secondary hyperparathyroidism
chronic kidney disease and vitamin D deficiency.
primary hyperparathyroidism signs and symptoms
asymptomatic
What are the causes of hypoparathyroidism?
The most common cause of hypoparathyroidism is accidental removal or damage to the parathyroid glands during surgery.
signs and symptoms hypoparathyroidism
muscle cramps and spasms, tingling or numbness in the hands and feet, and seizures.
investigations
blood tests to measure levels of calcium, phosphorus, and parathyroid hormone (PTH).
ultrasound or sestamibi scans may also be used to locate any abnormal parathyroid tissue.
treatment hyperparathyroidism
parathyroidectomy for primary hyperparathyroidism and symptomatic patients with secondary hyperparathyroidism
under 50 years
calcium >0.25 mmol/L above the upper limit of normal(2.85)
eGFR< 60 or presence of kidney stones
Non-surgical- fluids, vit D, cinacalcet (mimics effect of calcium on receptors)
treatment for hypoparathyroidism
mild >1.9mmol/L and asymptomatic
oral calcium
vit D if needed
Mg if needed
severe<1.9mmol/L or symptomatic
medical emergency
IV calcium
treat underlying cause
How does vitamin D deficiency affect PTH levels?
increased PTH secretion because calcitriol production is decreased. Without sufficient levels of calcitriol, calcium absorption in the intestines is reduced, leading to hypocalcemia. PTH is then released by the parathyroid glands in an attempt to raise blood calcium levels, but this can lead to hyperparathyroidism if left untreated.
How does excess vitamin D affect PTH levels?
Excess vitamin D can suppress PTH secretion by increasing calcium absorption in the intestines and reducing the need for PTH to be released by the parathyroid glands. This can lead to hypocalcemia if vitamin D levels are too high for an extended period of time.
What is the relationship between parathyroid hormone (PTH) and osteoclast activity?
stimulates osteoclast activity in the bones, which leads to bone resorption and the release of calcium into the bloodstream. When calcium levels in the blood are low, PTH is released by the parathyroid glands, which activates osteoclasts to break down bone tissue and release calcium into the bloodstream. This process helps to maintain normal blood calcium levels.
