2: Hyperparathyroidism Flashcards
What is hyperparathyroidism
High parathyroid hormone
What is primary hyperparathyroidism
Excess secretion PTH from parathyroid gland
What is secondary hyperparathyroidism
Hypocalcaemia leads to excess PTH secretion
What is tertiary hyperparathyroidism
Hypocalcaemia results in autonomous secretion of PTH from pituitary gland
What causes 80% of primary hyperparathyroidism
Pituitary adenoma
What are two other causes of primary hyperparathyroidism
- Hyperplasia (20%)
- Carcinoma (0.5%)
What is the main cause of secondary hyperparathyroidism
- CKD
What does CKD cause
Renal Osteodystrophy
What is another cause of secondary hyperparathyroidism
Vitamin D Deficiency
What causes tertiary hyperparathyroidism
Chronic Renal Failure
What is malignant hyperparathyroidism
Release of PTHrp by cancers
What 3 cancers release PTHrp
- Renal Cell Carcinoma
- Breast Cancer
- Squamous Cell Carcinoma
What endocrine disorder can parathyroid also be related to
Multiple Endocrine Neoplasia (MEN)
What is multiple endocrine neoplasia
Collection of hormone secreting tumours
What is the inheritance of MEN
Autosomal Dominant
What gene is mutated in MEN 1
MEN1 gene
How does MEN 1 usually present
Hypercalcaemia
What are the 3 P’s of MEN 1
- Parathyroid
- Pancreas (Insulinoma, Gastrinoma)
- Pituitary
What tumours are other tumours are present in MEN1
Adrenal
Thyroid
What gene is mutated in Men IIa
RET Oncogene
What cancer is men IIa most commonly associated with
Medullary Thyroid Cancer (90%)
What is medullary thyroid cancer
Cancer of C-cells
What are 2P’s of Men IIa
Pheochromocytoma
Parathyroid
What gene is mutated in men IIb
RET oncogene
What P is present in men IIb
Phaeochromocytoma
What other cancers occur in men IIb
- Neurofibromatosis
What is men IIb specially associated with
- Marfinoid body habits
- NF
What does neurofibromatosis cause
Bilateral vesicular schwanomas
How is hyperparathyroidism usually found
Incidentally, symptoms are often retrospective
What is the menumonic for symptoms of hypercalcaemia
stones, bones, groans and psychiatric overtones
Explain ‘stones’
Renal stones
Explain ‘bones’
- Pain
- Weakness
- Fractures
- Osteoporosis
Explain ‘groans’
- Tiredness
- Duodenal ulcer
- Pancreatitis
- Polyuria, Polydipsia
Explain ‘psychiatric overtones’
- Depression
What are symptoms of hyperparathyroidism due to BP
- HTN
what is the role of PTH
- Stimulates osteoclasts and hence bone reabsorption and serum calcium
- Inhibits phosphate reabsorption
- Increases vitamin D
explain renal osteodystrophy
- CKD reduces hydroxylation and activation of vitamin D
- This reduces calcium reabsorption in the gut and renal tubules - causing hypocalcaemia
- Hypocalcaemia causes hyperparathyroidism
- This leads to bone reabsorption
what is first-line investigation for hyperparathyroidism
Bone profile
what is adjusted calcium accounting for
Albumin.
As low albumin will cause hypocalcaemia on assay (despite normal calcium)
how will phosphate present in hyperparathyroidism
Low
when will PTH be high
1’ and 2’ hyperparathyroidism
explain PTH in malignant hyperparathyroidism
PTH will be low.
PTHrp released from cancers is not detected on the assay. However, will cause hypercalcaemia which activates negative feedback inhibiting PTH release
if pTH is normal what should you consider
lithium
thiazide diuretics
familial hypocalciuric hypocalcaemia
what is second line for hyperparathyroidism
X-ray
DEXA scan
what scan is used to detect pituitary adenoma
Technitium and Sestimibi scanning
what is osteitis fibrosa cystica
occurs due to severe periosteal reabsorption. Presents with:
- Brown tumours
- Erosions
- Cysts
- Pepper pot skull
how is mild hyperparathyroidism managed
Increase fluid intake (prevent stones)
Reduce calcium intake
what is first-line for moderate hyperparathyroidism
Parathyroidectomy
what are 4 indications of parathyroidectomy
- Osteoporosis
- Renal Stones
- High Serum Calcium
- Decrease renal function
what is an alternative to parathyroidectomy
calcimimmetics (cinacalcet)
what is role of cinacalcet
Increase sensitivity of chief cells to calcium and therefore reduces parathyroid secretion
what artery innervates parathyroid glands
Inferior thyroid artery
where do superior parathyroid glands arise
3rd pharyngeal pouch
where do inferior parathyroid glands arise
4th pharyngeal pouch
what can thyroid surgery lead to
hypocalcaemia
what is required to monitor following parathyroidectomy
Calcium
Phosphate
Magnesium
what is given following parathyroidectomy
Calcium
Vitamin D replacement
