Calcium Disorders COPY Flashcards
What are the common causes of hypercalcaemia?
90% are either:
- Primary Hyperparathyroidism
- Malignant Hypercalcaemia
OTher:
- Familial Hypocalciuric Hypercalcaemia (FHH)
- Drugs e.g. Thiazide diuretic or Lithium
- Sarcoid
What causes Primary Hyperparathyroidism?
85% are adenomas
~15% are 4 gland hyperplasia
Very rarely:
- MEN 1 or 2A
- Parathyroid Carcinoma
How does Hypercalcaemia present?
GI - Anorexia, Constipation & N&V
CV - Short QT, Hypertension & Bradycardia
Neuro - Loss of Conc. & confusion
Renal - Polyuria & Polydipsia + Nephrolithiasis
MSK - Muscle Weakness & bone pain
How does Primary Hyperparathyroidism present?
Its generally asymptomatic but can cause symptoms of hypercalcaemia
What is Familial Hypocalciuric Hypercalcaemia?
An autosomal dominant disorder causing Calcium-Sensing Receptor (CaSR) defects
What tests are appropriate for Hypercalcaemia?
hint theres loads
- Serum Ca, PO4, PTH & Albumin
- Serum ACE (Sarcoid)
- 24 hour urine collection for calcium (low = FHH)
- U&Es
- ALKP
- Lymph node exam (malignancy)
- Myeloma screen (osteolytic metastases)
- ECG (short QT)
- FH
- Med History
Abdo US for kidney stones
Parathyroid US for adedomas etc.
What are the initial tests for hypercalcaemia?
Serum Ca / PO4 / PTH / Albumin
FH & Med history
What are the “levels” of hypercalcaemia?
<3mmol/l - Generally aymptomatic
3-3.5mmol/l -~symptomatic & prompt treatment needed
> 3.5mmol/l - Emergency. Risks Dysrhythmia & coma
How do you treat hypercalcaemia first?
Rehydration & IV bisphosphonates (inhibit osteoclasts)
What can you give hypercalcaemics when bisphosphonates fail/arn’t tolerated?
Calcitonin
What treatments are there for lymphma or granulomatous disease causing hypercalcaemia?
Glucocorticoids e.g. Hydrocortisone
How would we treat Primary Hyperparathyroidism Hypercalcaemia?
Parathyroidectomy
OR
Calcimetics e.g. Cinacalcet
Summary of Hypercalcaemia treatments?
1st) Rehydrate and IV bisphosphonates
- Calcitonin
- Cinacalcet
- Parathyroidectomy
- Glucocorticoids
How does PTH differentiate the cause of Hypercalcaemia?
In hypercalcaemia PTH should be low.
If it is then the cause is outside the Parathyroid e.g. malignancy or drugs
If its high then theres some reason PTH is overproduced e.g. FHH, renal failure or Primary hyperparathyroidism
What are the main causes of Hypocalcaemia?
Low PTH aka hypoparathyroidism:
- Neck surgery e.g. thyroidectomy
- Autoimmune
- Magnesium Deficiency
- CaSR defect
High PTH (2nd* Hyperparathyroidism due to hypocalcaemia):
- Renal Disease
- Pseudohypoparathyroidism
- Pancreatitis
- Vit D deficiency
Inhibition of Bone resorption e.g. Bisphosphonates
What is Pseudohypoparathyroidism?
A set of disorders in which target organs like kidneys & bone become unresponsive to PTH
What causes pseudohypoparathyroidism?
- Agenesis e.g. Digeorge syndrome
- Destruction e.g. surgery
- Infiltration e.g. haemachromatosis or Wilson’s
- Hypomagnesaemia
- PTH resistance
What special about pseudohypoparathyroidism presentation?
Albright’s Hereditary Osteodystrophy (AHO):
- Obesity
- Short Stature
- Short Metacarpals
Low Ca
High PO4 & PTH (hence pseudo)
At what Serum Ca2+ level do symptoms of hypocalcaemia appear?
Around 1.9mmol/l
How does hypocalcaemia present?
Lots of symptoms, main ones are:
- Paraesthesia
- Muscle twitchin
- Trosseaus sign
- Chovstek’s Sign
Prolonged QT
Hypotension
Papilloedema
What are the named signs of hypocalcaemia?
Trosseau’s sign = Attach a tight BP cuff and watch the patients hand slowly form a claw
Chovstek’s Sign = Facial twitch when you tap on the parotid over the Facial nerve
What tests are appropriate for Hypocalcaemia?
Serum Ca, albumin, PO4
PTH (High Pseudoparathyroidism vs low Hypoparathyroidism)
Mg (Mg deficiency)
U&Es (renal failure)
Vit D (Vit D deficiency)
ECG
Explain how blood tests will appear for the 2 biggest causes of hypocalcaemia?
Vit D deficiency - Low Ca, low PO4 & high PTH
Hypoparathyroidism - Low Ca, High PO4 & low PTH
Also pseudoparathyroidism
- Low Ca, High PO4 and high PTH
How do you treat mild Hypocalcaemia?
Mild meaning >1.9mmol/l and asymptomatic.
Put them on oral Ca2+ suppleents
Also Oral Vit D tablets and Mg replacement as appropriate
How do you treat severe hypocalcaemia?
Severe meaning symptoms or <1.9mmol/l
Considered a medical emergency
IV Calcium Gluconate
Then treat cause
why do you test albumin?
Some calcium is albumin bound, to find a true serum calcium do serum calcium and serum albumin.
Then add 0.1mmol/l for every 5g/l reduction in Albumin from 40g/l
