Revision Flashcards by Thivyaa Gangatharan

2 hormones that increase calcium levels

PTH

Calctriol (vit D)

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Which hormone decreases calcium? Where is this produced?

Calcitonin - parafollicular cells

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Explain how vit D becomes activated

Vit D from diet and UV light is hydoxylated by liver to 25-hydroxy vit D.

Rate limiting step - this is then hydroxylated into activated vitamin D (calctriol) by 1alpha hyroxylase, which itself is activated by PTH.

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What is the effect of PTH on the bone, kidneys and small intestines? What is the overall effect?

Bone - increased resportion
Small intestines - increased absorption of calcium
Kidneys - increased calcium reabsorption and phosphate EXCRETION.

Overall effect - increased calcium, decreased phosphate

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What is the effect of calctriol on the bone, kidneys and small intestines? What is the overall effect?

Kidneys - increased calcium reabsorption
Bone - increased formation
Small intestines - increased calcium AND phosphate reabsorption

Overall - INCREASED calcium and phosphate

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Which hormone is better at increased calcium and dropping phosphate?

Vit D - better at increasing calcium than PTH

PTH - better at dropping phosphate (phosphate trashing hormone)

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PTH, ALP calcium and phosphate levels in primary hyperparathyroidism

High or INAPPROPRIATELY NORMAL PTH
Low phosh
High calcium
Normal ALP

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PTH, ALP calcium and phosphate levels in secondary hyperparathyroidism due to Vit D deficiency

Vit D low therefore:

Low calcium
Low phosphate
High PTH
High ALP because released by bone (osteomalacia)

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PTH, ALP calcium and phosphate levels in secondary hyperparathyroidism due to CKD

Kidneys not functioning, therefore:

High PTH
Low Calcium
However, high phosphate as kidneys can’t excrete it

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PTH, ALP calcium and phosphate levels in tertiary hyperparathyroidism

Tertiary hyperparathyroidism is secondary to CKD, therefore:

High PTH 
High calcium (no negative feedback)
High phosphate (because kidneys can't excrete it)

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If phosphate is low, what are you thinking?

Vit D deficiency or primary PTH

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If phosphate is high, what are you thinking?

CKD

If calcium is high too - tertiary
If calcium low - secondary

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Other causes of hypercalcemia

Malignancy

Bone mets
Haem - multiple -myeloma (CRAB)
Paraneoplastic - lung squamous cell cancer

Sarcoidosis
Thiazide diuretics

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Multiple myeloma acronym

Calcium high
Renal failure
Anemia
Bone disease

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Low PTH causes of low calcium

Surgical complications

Autoimmune hypoparathyroidism

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High PTH + low calcium

Osteomalacia (secondary hyperPTH)

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Low calcium symptoms

Convulsions
Arrhythmias - prolonged QT
Tetany (increased nerve conduction)
Paraesthesia - numb hands, mouth, feet, lips

CATS go numb

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Signs of hypocalcemia

Trousseau’s sign - spasm when tightening BP cuff

Chvostek’s sign - twtiching when touching facial nerve

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Which is more likely to be found in pancreatitis - hyper or hypocalcaemia?

Hypocalcemia due to saponification

High calcium causes pancreatitis but then it gets deposited.

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Risk factors for primary hyperparathyroidism

MEN 1 or 2

Hypertension

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MEN 1 complications

Pancreatic tumours
Parathyroid hyperplasia
Pituitary adenomas

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MEN 2 complications

Parathyroid hyperplasia
Phaeo
Medullary thyroid cancer

Causes of secondary hyperparathyroidism besides lack of sunlight/dietary intake if vit D

Crohns/Coeliac
CKD
Liver disease

Symptoms on secondary hyperparathyroidism in adults

Fractures/bone pain
Proximal myopathy (weakness)
Fatigue
Hypocalcemia symptoms - convulsions, arrhythmias, tetany, numbness

Invx

USS of parathyroid XR/CT Bn

XR findings in primary hyperparathyroidism

Subperiosteal bone resorption Acro-osteolysis (erosions of finger tips) Pepper pot skull

XR findings in secondary hyperparathyroidism

Swelling of constrochondral junctions - rachitic rosary Looser's pseudofractures - doesn't go all teh way

Treatment of acute hypercalcemia in primary hyperPTH

IV fluids | Bisphosphonates if calcium remains high

Treatment of hypercalcemia in primary hyperPTH once pt is stable

Total parathyroidectomy SE: risk of recurrent laryngeal nerve -> hoarseness

What do you give if a a patient with primary hyperPTH is unsuitable for surgery?

Cinacalcet, calcimimetic i.e. tries to do negative feedback against PTH like calcium

Secondary hyperPTH management in acute hypocalcemia

IV calcium infusion - calcium gluconate

What else is calcium gluconate used for?

Hyperkalemia

What would you give to a pt with secondary hyperPTH once they are stable?

Calcium | Vit D - ergocalciferol (inactive form)

How do you manage a pt with secondary hyperPTH with CKD once they are stable?

Calcium Vit D - alfacalcidol (active) Treat CKD

Three phases of paget's disease

``` Lytic phase (hyperactive osteoclasts causing resorttion) Mixed phase Sclerotic phase (hyperactive osteoblasts - woven bone, not lamellar) ```

Symptoms of Pagets

Often asymptomatic Fragility fractuers Bone pain - skull, femur, pelvis Nerve compression due to osteoblasts reforming the bone in areas where there used to be foramina - sensorineural hearing loss, sciatica

Signs of Paget's

Warm skin over painful area (high metabolism) | Bone enlargement

Blood findings in Paget's

High ALP, everything else normal

Name a bone resorption marker used in Pagets

Serum CTX

Name a bone formation marker used in Pagets

Serum P1NP

Imaging for pagets

XR | Tec99 scan - hot spots seen in high functioning areas of bone

PE scan if pregnant

V/Q scans

Osteoporosis primary causes

Menopause | Elderly

Osteoporosis secondary causes

``` Drugs: - Steroid use - Thyroxine - Alcohol Endo causes: - Cushing's - Hyperparathyroidism - Hyperthyroidism GI causes - Coeliac disease - IBD ```

Signs and symptoms in osteoporosis

Often asymptomatic Fragility fractures | Back pain

Osteoporosis fractures (four)

NOF Colles wrist fracutre Lumbar spine wedge fracture Neck of humerus

Imaging for osteoporosis

DEXA scan | XR

Blood results for osteoporosis

Everything normal

What are the two types of scores used in DEXA? Which of these is most important?

T score - patient's BMD compared to young, healthy adults - most important Z score - patient's BMD compared to age matched BMD

What numbers are key in diagnosing osteoporosis and also the stage before that, using DEXA scans?

- 1 to -2.5 -> osteopenia | - 2.5 or above - osteoporosis

What is the DEXA score used to calculate?

The FRAX score aka 10 year risk of developing fragility fractures; decides management

Looser's pseudofracture

low vit D and calcium

Osteoporosis mx

Bisphosphonates | Recombinant PTH - teriparatide