Disorders of Calcium homeostasis Flashcards
(47 cards)
What are the clinical manifestations of hypercalcaemia?
‘Stones, bones, abdominal moans and psychic groans’
Includes muscle weakness, central effects, renal effects, bone involvement, abdominal pain, and ECG changes.
What are the central effects of hypercalcaemia?
- Anorexia
- Nausea
- Mood change
- Depression
What renal effects are associated with hypercalcaemia?
- Impaired water concentration
- Renal stone formation
What ECG changes are seen in hypercalcaemia?
Shortened QT interval
What is factitious hypercalcaemia?
Raised [calcium] due to high plasma [albumin]
What are some causes of factitious hypercalcaemia?
- Venous stasis
- Dehydration
- IV albumin
What is the prevalence of primary hyperparathyroidism?
1 in 500 to 1 in 1000
In which decade is primary hyperparathyroidism most common?
6th decade
What is the gender ratio for primary hyperparathyroidism?
Women > men, 3:2 ratio
What is the most common etiology of primary hyperparathyroidism in outpatients?
90% solitary adenoma; hyperplasia; carcinoma (rare)
What distinguishes 1y hyperparathyroidism from 2y and 3y?
1y is autonomous overproduction of PTH; 2y is appropriate increase in PTH due to hypocalcaemia; 3y is rare overactivity of a 2y gland.
What are the diagnostic criteria for 1y hyperparathyroidism?
Raised Ca2+ with inappropriately increased PTH
What happens to phosphate and bicarbonate levels in 1y hyperparathyroidism?
They tend to be low in serum.
What imaging technique is used for parathyroid diagnosis?
Sestamibi scan (99m Tc-MIBI)
What is the acute treatment for high ionised calcium in 1y hyperparathyroidism?
- Re-hydration
- Drugs
What is the definitive treatment for 1y hyperparathyroidism?
Removal of parathyroid adenoma (surgery)
What drugs are used to treat hypercalcaemia?
- Bisphosphonates
- Furosemide
- Calcitonin
- Glucocorticoids
What is the mechanism of action for bisphosphonates?
Inhibit osteoclast action and bone resorption
What is the most common cause of hypercalcaemia in hospitalised patients?
Malignant disease
What percentage of cancer patients may develop hypercalcaemia?
20-30%
What are the two broad reasons for hypercalcaemia in malignancy?
- Endocrine factors secreted by malignant cells
- Metastatic tumour deposits in bone
What tumour types commonly cause hypercalcaemia?
- Lung (35%)
- Breast (25%)
- Haematological (14%)
- Head & Neck (6%)
- Renal (3%)
- Prostate (3%)
- Unknown primary (3%)
- Others (3%)
What is humoral hypercalcaemia of malignancy?
Caused by PTH-related peptide (PTHrP) secreted by solid tumours.
What diagnosis is indicated by raised Ca2+ with suppressed PTH?
Malignancy