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It is written in FA:

Secondary hyperthyrodism: 2° hyperplasia due to  Ca2+ absorption
and/or increased PO4, most often in chronic renal disease (causes hypovitaminosis D -> decreased Ca2+ absorption). Hypocalcemia, hyperphosphatemia in chronic renal failure (vs. hypophosphatemia with most other causes), increased ALP, increased PTH.

Tertiary: Refractory (autonomous) hyperparathyroidism resulting from chronic renal disease. Increased PTH, increased Ca2+.

Why there is hypocalcemia in secondary hyperparathyrodism and hypercalcemia in tertiary hyperparathyrodism although both due to chronic renal failure? Can anyone tell the difference between both?
 

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It is written in FA:

Secondary hyperthyrodism: 2° hyperplasia due to  Ca2+ absorption
and/or increased PO4, most often in chronic renal disease (causes hypovitaminosis D -> decreased Ca2+ absorption). Hypocalcemia, hyperphosphatemia in chronic renal failure (vs. hypophosphatemia with most other causes), increased ALP, increased PTH.

Tertiary: Refractory (autonomous) hyperparathyroidism resulting from chronic renal disease. Increased PTH, increased Ca2+.

Why there is hypocalcemia in secondary hyperparathyrodism and hypercalcemia in tertiary hyperparathyrodism although both due to chronic renal failure? Can anyone tell the difference between both?
Normally Increased PTH -increased ca , decreased phosphate levels

in CRF-
low levels of ca -secondary to decreased vit D / binding of ca to high levels of phosphate
high levels of phosphate - due to decreased excretion of phosphate by kidneys

this low ca/high phosphate- stimulate the glands to increase PTH levels.

Tertiary HyperPTH- occurs in some cases of CRF- here PT glands become autonomous regardless of the ca levels. {GOLJAN}
 
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