Calcium And Parathyroid Hormone 07.12.23 Flashcards
Parathyroid hormone actions
Slide 4
What Does a small change in serum calcium result in a large or small change in PTH?
Large - slide 8
Hypocalcaemia - what two measurements in the blood are low?
Low total serum calcium and low ionised calcium
What is the equation for corrected calcium?
Total serum calcium + 0.02 * (40 - serum albumin)
Consequences of hypocalcaemia
Parasthesia (pins and needles)
Muscle spasm (hands and feet, larynx, premature labour)
Seizures
Basal ganglia calcification
Cataracts
ECG abnormalities (long QT interval)
What are the 2 signs used to check for hypocalcaemia
Chvostek’s sign (tap over the facial nerve, look for spasm of facial muscles)
Trousseau’s sign (inflate the blood pressure cuff to 20mm Hg above systolic for 5 minutes)
What are the common symptoms and consequences of hypercalaemia?
Thirst (polyuria)
Nausea
Constipation
Confusion —> coma
Renal stones
ECG abnormalities (short QT)
Causes of hypercalcaemia
Malignancy —> bone mets, myeloma, PTHrP, lymphoma
Primary hyperparathyroidism
What % of hypercalcaemic cases are caused by malignancy or primary hyperparathyroidism
90%
Other 10% is thiazides, thyrotoxicosis, sarcoidosis, familial hypocalciuric/benign hypercalcaemia, immobilisation, milk-alkali, adrenal insufficiency, phaeochromocytoma
Consequences of primary hyperparathyroidism
Bones (osteitis fibrosis cystica, osteoporosis)
Kidney stones
Psychic groans (confusion)
Abdominal moans (constipation, acute pancreatitis)
In cases of primary hyperparathyroidism, 80% are due to what
Single benign adenoma
In cases of primary hyperparathyroidism, 15-20% are due to what
Four gland hyperplasia
See parathyroid handout (word doc)