calcium and parathyroid hormone Flashcards
actions of parathyroid hormone
- Increased Ca2+ reabsorption in the kidney
- Increased 1 alpha-hydroxylation of 25-OH vitamin D in the kidney
- Decreased phosphate reabsorption in the kidney
- Increased bone remodelling (bone resorption greater than bone formation)
- Indirectly increases Ca2+ reabsorption in the intestine
what is hypocalcemia
Low total serum calcium
consequences of hypocalcaemia
Paraesthesia
Muscle spasm
Seizures
Basal ganglia calcification
Cataracts
ECG abnormalities (long QT)
Causes osteomalacia – vitamin D deficiency
what is corrected calcium
total serum calcium + 0.02
what is Chvostek’s sign
tap over facial nerve and look for spasm of facial muscles
what is hypoparathyroidism
Underproduction of parathyroid hormone.
causes of hypoparathyrodism
- Genetics – recessive, dominant, X-linked
- Autoimmune – isolated, polyglandular type 1
- Infiltration of the parathyroid glands by iron overload (hemochromatosis)
- Surgery - parathyroidectomy (removal of parathyroid glands)
what is Pseudohypoparathyroidism
Resistance to parathyroid hormone
what is calcium like in Pseudohypoparathyroidism
Normal calcium metabolism
Low serum calcium and high phosphate but appropriate PTH level for the low calcium
consequnces of Pseudohypoparathyroidism
Short stature
Obesity
Round faces
Mild learning difficulties
Short fourth metacarpals
Other hormone resistance
define hypercalcaemia
High calcium levels in the blood serum (>2.66mmol/L)`
what can cause hypercalcaemia
by tourniquet on for too long
symptoms of hypercalcaemia
Thirst
Polyuria
Nausea
Constipation
Confusion
Can lead to coma
consequences of hypercalcaemia
Malignancy (lymphoma)
Primary hyperparathyroidism
Thiazides
Sarcoidosis
what is primary hyperparathyroidms
Increased PTH levels usually due to a tumour within the parathyroid gland
consquences of primary hyperparathyroidism
Bones – osteitis fibrosa cystica, osteoporosis
Kidney stones
Psychic groans – confusion
Abdominal moans – constipation, acute pancreatitis
PTH, Calcium, phosphate levels in Vitamin D deficiency (secondary hyperparathyroidism
PTH - high
calcium - low
phosphate - low
PTH, Calcium, phosphate levels in Hypoparathyroidism (underactive parathyroid)
PTH - low
calcium - low
phosphate - high
PTH, Calcium, phosphate levels in Pseudohypoparathyroidism (hypocalcaemia - PTH resistance)
PTH - high
calcium - low
phosphate - high
PTH, Calcium, phosphate levels in Pseudopseudohypoparathryoidism (pseudo phenotype, Ca metabolism normal)
PTH - normal
calcium - normal
phosphate - normal
PTH, Calcium, phosphate levels in Hypercalcaemia of malignancy
PTH - low
calcium - high
phosphate - Unpredictable - depends on underlying cause
PTH, Calcium, phosphate levels in Primary hyperparathyroidism
PTH - high
calcium - high
phosphate - low
PTH, Calcium, phosphate levels in tertiary hyperparathyrodism
PTH - high
calcium - high
phosphate - high
is PTH appropiate in Vitamin D deficiency (secondary hyperparathyroidism
yes
is PTH appropiate in Hypoparathyroidism (underactive parathyroid)
no
is PTH apprioiate in Pseudohypoparathyroidism (hypocalcaemia - PTH resistance)
yes
is PTH appropiate in Pseudopseudohypoparathryoidism (pseudo phenotype, Ca metabolism normal)
n/a
is PTH appropiate in Hypercalcaemia of malignancy
yes
is PTH appropiate in Primary hyperparathyroidism
no
is PTH appropiate in tertiary hyperparaythyroidism
no
when are changes in PTH appropiate
To maintain calcium balance
when are changes in PTH inappropiate
they Cause calcium imbalance
