Step I renal and endo question

[daisygirl]

Is this a mistake in first aid?-
The thin descending loop of henle passively reabsorbs water via medullary hypertonicity (impermeable to sodium).

I thought the thin descending loop absorbed na/cl and urea while secreting water in order to help create the countercurrent, while the thin ascending was impermeable to water but secreted na/cl and urea. 😕

One more question, but on endo this time- Why does a large decrease in extracellular mg cause hypoparathyroidism? I am aware that a small decrease in extracellular mg causes PTH secretion. Is mg involved in the cAMP secondary messenger system? I have a vague memory that it is and that is why a large decrease in extracellular mg results in hypoparathyroidism.

 

[Idiopathic]

Is this a mistake in first aid?-
One more question, but on endo this time- Why does a large decrease in extracellular mg cause hypoparathyroidism? I am aware that a small decrease in extracellular mg causes PTH secretion. Is mg involved in the cAMP secondary messenger system? I have a vague memory that it is and that is why a large decrease in extracellular mg results in hypoparathyroidism.

Magnesium is a cofactor required for the action of PTH, so it is really a functional hypo-PTH. The most common cause of hypocalcemia in a hospitalized patient is hypo-magnesemia (affecting PTH)

 

[daisygirl]

Magnesium is a cofactor required for the action of PTH, so it is really a functional hypo-PTH. The most common cause of hypocalcemia in a hospitalized patient is hypo-magnesemia (affecting PTH)

Then would I be correct to assume that the PTH levels would be elevated in hypo-magnesemia?

Thanks for your help 🙂

 

[Idiopathic]

Sorry, magnesium is a cofactor for the production of PTH, so PTH is actually decreased. I misspoke earlier, this would be primary hypo-PTH.