Parathyroid Pathology Flashcards
Describe the pathophysiology of hypocalcaemia?
Neurons are more excitable
What are the causes of hypocalcaemia?
Primary hypoparathyroidism
- Total thyroidectomy
- Selective parathyroidectomy
- Post-radiation
Severe vitamin D deficiency
Hypomagnesaemia Mg2+ deficiency
Cytotoxic drug-induced hypocalcaemia
Hypoalbuminaemia
Acute pancreatitis
Pseudohypoparathyroidism
Pseudopseudohypoparathyroidism
What is Pseudohypoparathyroidism?
Cells resistant to PTH
Pixie face, short metacarpals and metatarsals
What is Pseudopseudohypoparathyroidism?
Same morphological features as pseudohypoparathyroidism, but normal biochemical profile
How does hypocalcaemia present?
SPASMODIC
Parathesia
Seizures/tetany
Disorientation/dementia
Dry skin/Impetigo
Muscle twitching/spasms
What is Trousseau’s sign?
Wrist spasm
What is Chovstek’s sign?
Facial twitching
What is Carpopedal Spasm?
Feet or hand spasm
What investigations are used in hypocalcaemia diagnosis?
<ca2>
<p>Vitamin D</p>
<p><pth>
<p>Albumin</p>
<p>Magnesium</p>
<p>Phosphorus</p>
<p>ECG: Prolonged QT</p></pth></p></ca2>
How is hypocalcaemia managed?
Calcium and Vitamin D supplements
Recombinant human Parathyroid hormone
Give complications of hypocalcaemia
Hypotension
HF
Arrythmia
Laryngospasm/Bronchospasm
Describe the pathophysiology of hypercalcaemia
Neurons are less excitable
What causes hypercalcaemia?
Hyperparathyroidism
- Adenoma
- Carcinoma
- Hyperplasia
Bone Metastasis
- Lung
- Breast
Renal disease
Sarcoidosis
Endocrine
- Acromegaly
- Addisons
- Thyrotoxicosis
Drugs
Dehydration
Familial Hypocalciuric Hypercalcaemia
What is the most common cause of hypercalcaemia?
Malignancy is most common in hospital, whereas hyperparathyroidism is most common in the community
How does hypercalcaemia present?
Stones, groans, bones and moans
Dehydration: Loss of calcium in urine
Bone pain: De-mineralisation to release Ca2+
Muscle weakness
Polydipsia/polyuria: Diabetes Insipidus
Confusion: Especially in the elderly
Depression
Constipation
What investigations are used in hypercalcaemia diagnosis?
>Ca2+
>PTH (can also be normal in primary hyperparathyroidism)
PTH-related peptide
Vitamin D
TFTs
Tumour markers
ECG, shortened QT interval
Imaging
- Bone scan
- CXR
- Mammogram
How is hypercalcaemia managed?
IV fluids, first line
Loop diuretics
Parathyroidectomy
Bisphosphonates
Calcimimetics, drugs that imitate calcium
When is a parathyroidectomy carried out?
If Ca2+>3mmol/l + symptomatic/renal stones
Give an example of a bisphosphonate?
Alendronate
What is a complication of hypercalcaemia?
Kidney/gallbladder stones
What is secondary hyperparathyroidism?
Raised PTH in response to low calcium
What is tertiary hyperparathyroidism?
Prolonged/untreated secondary hyperparathyroidism occuring almost exclusively in patients with kidney disease causing ongoing hyperplasia the gland
What causes hyperparathyroidism?
Solitary parathyroid adenoma
Hyperplasia of parathyroid gland
Autoimmune
HIV
DiGeorge
Multiple Endocrine Neoplasia (MEN) Syndromes 1 and 2
Secondary: Renal failure, Vitamin D deficiency
What is the most common cause of hyperparathyroidism?
Solitary parathyroid adenoma, 85% of causes
How is hyperparathyroidism managed?
High fluid intake
- To prevent stone formation
Surgical resection of parathyroid gland
What is a complication of hyperparathyroidism?
Risk of transient hypocalcaemia post-operatively
What conditions are associated with Multiple Endocrine Neoplasia (MEN) 1?
Hyperparathyroidism/parathyroid adenoma
Pancreatic
- Insulinoma
Pituitary
What conditions are associated with Multiple Endocrine Neoplasia (MEN) 2?
Hyperparathyroidism
Phaechromocytoma
Medullary thyroid cancer
What electrolyte abnormality is associated with hypercalcaemia?
Hypernatraemia
What is important to note about PTH levels in primary hyperparathyroidism?
PTH may be normal
What drugs can cause hypercalcaemia?
Thiazide diuretics
When is an IV biphosphonate indicated?
Ca over 3 mmoles/l
Describe the hormone profile of primary hyperparathyroidism
increased or inappropriately normal PTH
increased Ca
decreased phosphate
increased ALKP
Describe the hormone profile of secondary hyperparathyroidism
increased PTH
normal or decreased Ca
increased phosphate
decreased vit D
Describe the hormone profile of tertiary hyperparathyroidism
significantly increased PTH
normal or increased Ca
normal or decreased phosphate
normal or decreased vitamind D
increased ALKP
What x-ray sign can be seen in hyperparathyroidism?
Pepper pot skull
How is hypomagnesaemia managed?
<0.4 mmol/L or tetany, arrhythmias, or seizures
- IV magnesium replacement
>0.4 mmol/l
- Oral magnesium salts, although diarrhoea can occur
