Calcium dysregulation Flashcards
what does FGF23 do?
- Derived from osteocytes
- Phosphate regulation by kidney reabsorption by inhibiting these transporters
- Inhibits calcitriol to lower phosphate
What are hypocalcaemia symptoms?
Paraesthesia (hands, mouth, feet , lips)
Convulsions
Arrhythmias
Tetany
What is hypocalcaemia?
Sensitises excitable tissues; muscle cramps, tetany, tingling
What are the signs of hypocalcaemia?
- Chvosteks’ sign – facial paresthesia *zygomatic arch of the facial nerve
- Trousseau’s sign – carpopedal spasm
How does low PTH cause hypocalcaemia?
Hypoparathyroidism due to:
- Neck surgery
- Autoimmune
- Magensium defiency
- Congenital
How does low Vitamin cause hypocalcaemia?
Deficiency :
- Diet
- UV light
- malabsorption
- Impaired production ( renal failure )
What are the signs of hypercalcaemia?
‘Stones, abdominal moans and psychic groans’
Reduced neuronal excitability – atonal muscles
What does it mean by ‘stones’ in hyperCa?
renal effects
Nephrocalcinosis – kidney stones, renal colic
What does it mean by ‘Abdominal moans’ in hyperCa?
GI effects
Anorexia, nausea, dyspepsia, constipation, pancreatitis
What does it mean by ‘Psychic groans’ in hyperCa?
CNS effects
Fatigue, depression, impaired concentration, altered mentation, coma (usually >3mmol/L)
what are the causes of hypercalcaemia?
Primary hyperparathyroidism:
- parathyroid gland adenoma
- no negative feedback so notice high PTH but high Calcium
Malignancy:
- Bony metastases produce local factors to activate osteoclasts
- Cancers e.g. squamous cell carcinomas secrete PTH-related peptide that acts atPTH receptors
Vit D excess : rare
What is the biochemistry of hyperparathyroidism?
High calcium
Low phosphate ( due to increased renal excretion- inhibition of Na+/PO43- transporter )
High PTH
What can occur if hyperparathyroidism is not treated?
- Osteoporosis
- Renal Calculi
- Psychological impact e.g. mental function, mood
What is the treatment choice for primary hyperparathyroidism?
Parathyroidectomy
What is the biochemistry of secondary hyperparathyroidism?
Low Calcium
PTH high secondary to low calcium
Normal physiological response to hypocalcaemia
What are the causes of secondary hyperparathyroidusm?
Calcium deficiency due to vit D deficiency
less common : renal failure causing calitriol to not be made
How to treat secondary hyperparathyroidism?
Vit D replacement:
- 25 hydroxy vitaminD
body then creates calcitriol itself
How to treat secondary hyperparathyroidism? in px wil renal failure?
- inadequate 1a hydroxylation, so can’t activate 25 hydroxy vitamin D preparations
Give Alfacalcidol -
1alpha hydroxycholecalciferol
What is tertiary hyperparathyroidism?
Chronic renal failure
Chronic vit D deficiency
Decreased calcium
Causes excessive PTH release cause of chronic nature and is hard to turn off
How to treat tertiary hyperparathyroidism?
parathyroidectomy = will need to remove the gland to control ( have 4 glands so remove 1 )
What diagnostic approach should you use when looking at hypercalaemia?
When you see a px with high calcium always look at PTH
Biochemistry due to malignancy hypercalaemia?
High calcium (hypercalcaemia) Low/suppressed PTH
What if patient with hypercalcaemia has raised PTH?
- has raised PTH, the diagnosis is hyperparathyroidism
- Primary hyperparathyroidism if renal function is normal (eg parathyroid adenoma)
- Tertiary hyperparathyroidism (all 4 glands enlarged – hyperplastic) if chronic renal failure
How is Vit D measured?
measured as 25 (OH) vitamin D
Calcitriol (1,25 dihydroxy vitamin D) is very difficult to measure
In low calcium PTH will be high secondary to low calcium
