Diseases of the parathyroid glands Flashcards
What is the primary cause of hyperparathyroidism
Parathyroid adenoma - hypersecretion of PTH
What is the secondary cause of hyperparathyroidism
Physioloical compensation of all parathyroid hormones - hypertrophy due to hypocalcaemia
What is a tertiary cause of hyperparathyroidism
Adenomas arising from patients with secondary hyperparathyroidism - These hyper secrete
What are the symptoms of primary hyperparathyroidism
- Renal stones
- Muscle weakness
- Tiredness
- Thirst
- Anorexia and constipation
- Peptic ulcers as gastric secretion ins enhanced
Why are renal stones common in primary hyperparathyroidism
Due to hypercalciurea
What are four causes of hypercalcaemia
- Malignancy in bones
- Hyperparathyroidism
- Vitamin D intoxication
Two actions of vitamin D
Intestines - Increases Ca absorption
Bone - With PTH, releases Ca into circulation (needed for mineralisation of osteoids)
What three things do we look out for in patients when hypercalcaemia points towards hyperparathyroidism as a cause
- Raised plasma calcium conc. and LOW phosphate conc.
- Mild metabolic acidosis
- Raised PTH levels
What are 80% of primary hyperparathyroidism caused by
Secretory adenoma of one of the parathyroid glands
What is 20% of primary hyperparathyroidism caused by
Hyperplasia of all parathyroid glands
How is hyperparathyroidism managed
- Inspection of all parathyroid glands + removal of suspected adenoma
5 Clinical features of hypoparathyroidism
(same as clinical features of hypocalcaemia)
- tetany (look at larynx, hands and feet or premature labour)
- Convulsion
- Psychiatric disturbances
- Cataracts
- Paraesthesiae
What is Tetany
Skeletal muscle spasms
What is Paraesthasiae
Abnormal dermal sensations (itching, burning) with no physical stimuli
How is hypoparathyroidism diagnosed
- Hyperphosphataemia
- Rickets due to vitamin D deficiency
- Excessive loss during lactation
AND mainly due to low PTH levels
What are three main causes of hypoparathyroidism
- Removal of parathyroid glands during surgery
- Idiopathic hypoparathyroidism
- DiGeorge syndrome
What is idiopathic hypoparathyroidism and when does it occur
Childhood
Hypoparathyroidism that occurs suddenly with no reason (idiopathic)
How is idiopathic hypoparathyroidism caused
Destruction of parathyroid cells by an autoantibody
How many parathyroid glands do adenomas effect
Only one usually
How to calculate corrected calcium levels
Total serum calcium + 0.02*(40-serum albumin)
Why do we need to correct calcium levels in measurements
Because we could have a low serum calcium level but a high ionised calcium ion level
What are two tests we can do as doctors to check for hypocalcaemia
- Chvostek’s sign (Tap over facial nerve and see if facial muscles spasm)
- Trousseau’s Sign (Inflate blood pressure cuff to 20mm Hg above systolic for 5 minutes)
REMEMBER: SPASMODIC S - Spasms P - Perioral paraesthesia A - Anxious S - Seizures M - Muscle tones increases - wheeze O - Orientation impaired D - Dermatitis I - Impetigo Herpetiformis (reduced Ca and pustules in pregnancy) C - Chvostek's Sign, Cataract and Cardiomyopathy
Describe how the Trosseau’s Sign help’s detect for hypocalcaemia
- Occludes brachial artery
- In absence of blood flow, neuromuscular irritability will cause spasm of hand
- Wrist and metacarpophalangeal joins flex
- DIP and PIP joints extend
Looks like a camp hand
Role of Vit D in immunity
Induces differentiation
What is DiGeorge Syndrome
Deletion of chromosome 22 - causes abnormality in 3rd and 4th branchial pouches
- Cleft Palate
- Hypoparathyroidism
- Immunodeficiency
- Kidney problems
What autoimmunity causes hypoparathyroidism
Polyglandular type I
- Recessive disorder located on chromosome 21
Why is hypoparathyroidism caused by magnesium
Because a low, constant level is needed for parathyroid secretion of calcium. If it gets too low, then secretion is inhibited
role of magnesium in the body
- Magnesium is needed to relax muscles whilst calcium is needed to contract them.
- Provides elasticity and flex
Effect of decreased PTH production in hypoparathyroidism
- Decreased renal absorption of Ca
- Increased renal absorption of phosphates
- Decreased bone resorption
- Decreased formation of 1,25(OH)2D
What is pseudohypoparathyroidism
Resistance to PTH
What is Albright hereditary osteodystrophy
Mutation with deficient G-alpha subunit (pseudohypoparathyroidism type 1)
Signs of pseudohypoparathyroidism type 1a
- Short stature
- Obesity
- Learning difficulties
- Short fourth metacarpal
- Subcutaneaous ossification
Albright
Sign of pseudohypoparathyroidism type 1b
Mild brachydactyly
How is type 1b pseudohypoparathyroidism caused
Methylation defect
Is type 1b similar to 1a
Biochemically but not physically when seen in an individual
In what way is type 2 different to type 1a and 1b
Genetic defect is further down the signalling pathway than in type 1 so cAMP response to PTH works here
3 ways pseudohypoparathyroidism effects the body
- reduced Bone resorption
2. reduced Ca absorption
What is pseudopseudohypoparathyrodiism
Where an individual has the phenotype of pseudohypoparathyroidism type 1a but normal levels of Ca and PTH in the blood
Two circumstances when calcium levels are high in the blood but there do not have hypercalcaemia
- Torniquet on for too long
2. Sample is old and has haemolysed
Hypocalcaemia vs hypercalcaemia in ECGs
Hypo - Long QT interval
Hyper - Short QT
What is sarcoidosis
Abnormal collections of inflammatory cells that form granulomas
What is osteitis fibrous cystica and in which condition is this seen in
- Loss of bone mass and weakening of calcified supporting structures
- Primary hyperparathyroidism
Why would a patient with primary hyperparathyroidism have abdominal moans
- Constipation
2. Acute pancreatitis
In what sex are thyroid problems more common in
Females
Why is the thyroid highly vascularised
As it secretes hormones directly into the blood
Lab results for primary hyperparathyroidism
High PTH
High Ca
Low Phosphate
High Alkaline Phosphatase
Symptoms of secondary hyperparathyroidism
Joint pain and osteomalacia (low mineral content of bone)
Lab results for secondary hyperparathyroidism
REMEMBER: Secondary is usually seen in Chronic Kidney Disease and Chrohn’s Disease
High PTH
Low Ca
High Phosphate (renal disease)
High Alkaline Phosphate
Can symptoms for secondary hyperparathyroidism be seen
No - asymptomatic
Lab results for tertiary hyperparathyroidism
High PTH
High CA
High Phosphate
High Alkaline Phosphatase
How is malignant hyperparathyroidism caused
Parathyoroid-related protein is produced by squamous cell lung cancers and breast cancers which mimic PTH (PTH levels are low in labs)
Bone infiltration
Production of osteoclastic factors by tumours
What drugs would be given to treat malignant hyperparathyroidism
- Thiazide diuretic
- Vit D analogies
- Lithium administration
And long-term immobility
What is the first presenting symptom of malignant hyperparathyroidism
Hypercalcaemia
What is the patient suffering from if they are overall very healthy but have hypercalcaemia
Primary hyperparathyroidism NOT malignant
How do we go from primary to tertiary hyperparathyroidism
Long-standing pathology
What blood component would exclude hyperpaarthyroidism in lab results
LOW PTH levels - Malignant
Lab results for Malignant hyperparathyroidism
- Low albumin
- Low PTH
- Raised alkaline phosphatase
What do we do if the following was found:
- Low albumin
- Low PTH
- Raised alkaline phosphatase
Protein electrophoresis t look for myeloma
What is myeloma
Cancer of plasma cells in the bone marrow
What would we see in electrophoresis if myeloma is positive
B2-microglobulin will be present
What would low renal function indicate
Secondary or tertiary hyperparathyroidism
What would we detect to exclude all type of hyperparathyroidism in the patient
Measure TSH levels
DXA bone density scan - could diagnose osteoporosis instead
How do we detect a patient for parathyroid tumours
Radioisotope scanning (90% sensitive)
What might be a more effective replacement for radioisotope scanning
High res CT or MRI is more sensitive
How is acute severe hypercalcaemia treated
- Rehydrate with IV 0.9% saline - prevents stones
- Bisphosphates (prevents bone resorption by inhibiting osteoclasts) after rehydration (IV Pamidronate)
- Measure serum and U+Es daily and serum Ca 48 hours after treatment
- Give glucocorticoids steroids (ORAL PREDNISOLONE)
How do we treat [rimary hyperparathyroidism
Surgically remove adenoma
OR
Surgically remove all four glands if its parathyroid hyperplasia
What is the complication of post-op primary hyperthyroidism surgery
Hypocalcaemia
What would we give to treat post-op hypocalcaemia in patients with primary hyperparathyroidism that just had surgery
Oral Cinacalcet - Calcimimetic that increases sensitivity of parathyroid glands to Ca
Would we give Thiazide diuretic to patients with primary hyperparathyroidism
No, we avoid them and high Ca and Vit D intake
How is pseudopseudohypoparathyroidsm inherited
Father
Drugs to treat hypocalcaemia
- Calcitonin
- Bisphosphates
Reduces Ca plasma conc
How is acute hypoparathyroidism treated
IV CALCIUM GLUCONATE for 30 mins with ECG monitoring
How to treat Vit D deficiency
- Give Oral Colecalciferol (Vid D3) OR Oral Adcal (calcium and vit D3)
How is non-acute hypoparathyroidism treated
Calcium supplements and Calcitriol
What is Calcitriol
Activated Vit D
