Endocrine_CCT (3) Flashcards
What does PTH hormone do?
- increases the osteoclast activity releasing Ca2+ and PO43-from the bones
- Increase calcium and decreases PO43-reabsorption in the kidney
- Active 1,25, dihydroxy-vitamin D3 production is overall increased.
- Increases calcium decreases PO43-
Causes of Primary Hyperparathyroidism
- Solitary adenoma or hyperplasia of the glands
- There is a very low chance that they are caused by parathyroid cancers
Presentation of hyperparathyroidism
- Often asymptomatic with an increase of calcium in routine tests
- Weakness
- Tired
- Depressed
- Thirsty
- Dehydrated but polyuria
- Renal stones
- Abdominal pain
- Pancreatitis
- Ulcers -duodenal more than gastric
Signs which indicate an increase in calcium are__:
- Bone reabsorption effects on PTH can cause pain, fractures and osteopenia/osteoporosis
- Increase in blood pressure so check the calcium levels in everyone that presents with hypertension
Ix of primary hyperparathyroidism
- High calcium and high PTH
- Low PO43-
- Alk Phos is increased from bone activity
- 24 hour urinary calcium is increased
- Subperiosteal erosion
- Brown tumours of phalanges + acro-oesikysis + pepper pot skull DEXA
If patient is on which (2) meds, Ca++ and PTH levels may be normal in hyperparathyroidism?
Thiazide diuretics and lithium
Management of primary hyperparathyroidism
- If mild -more fluid intake to prevent the stones and avoid thiazides and high calcium intake as well as vitamin D
- Excision of adenoma or all of the hyperplastic glands as this will prevent the fractures and the peptic ulcers
Secondary parathyroidism
- abnormality in levels
- cause
- management
Low calcium and high PTH
Cause: low vitamin D intake, and chronic renal failure
Management: correcting the causes, phosphate binders, vit D, cinacalcet, parathyroidectomy is tricky
*as kidney is # and has difficulty to excrete phosphate (PO43-) -> less Ca++ produced
Tertiary hyperparathyroidism
- levels
- causes
High calcium and very very high PTH
Cause: after prolonged secondary hyperparathyroidism -> the glands act autonomously having to undergo hyperplastic or adenomatous change
- increase of Ca from the increase of secretion of PTH unlimited by the feedback control
- seen in chronic renal failure.
What cancers may cause hyperparathyroidism?
- Parathyroid-related protein is produced by some squamous cell lung cancers, breast and renal cell carcinomas
- mimics the PTH resulting in an increase in Ca and low PTH
Primary hypoparathyroidism
- levels
- signs (in general)
- causes
- management
Primary hypoparathyroidism
↓Ca2+, ↑PO43−or ↔, ↔alp
PTHsecretion is ↓due to gland failure
Signs:
Those of hypocalcaemia,± autoimmune comorbidities
Causes:
Autoimmune; congenital (Di George syn.,OHCS)
Management
Ca2+supplements + calcitriol
What is Pseudohypoparathyroidism?
- target cells being insensitive to PTH
- due to abnormality in a G protein (genetic)
- associated with low IQ, short stature, shortened 4th and 5th metacarpals
- low calcium, high phosphate, high PTH
- diagnosis is made by measuring urinary cAMP and phosphate levels following an infusion of PTH. In hypoparathyroidism this will cause an increase in both cAMP and phosphate levels. In pseudohypoparathyroidism type I neither cAMP nor phosphate levels are increased whilst in pseudohypoparathyroidism type II only cAMP rises.
What is Pseudopseudohypoparathyroidism?
Pseudopseudohypoparathyroidism
- similar phenotype to pseudohypoparathyroidism but normal biochemistry
Causes of hypernatraemia
Causes of hypernatraemia
- dehydration
- osmotic diuresis e.g. hyperosmolar non-ketotic diabetic coma
- diabetes insipidus
- excess IV saline
Clinical presentation of hypernatraemia
- Severe symptoms mainly develop when the serum [Na+] > 160mmol/l.
- more severe with acute hypernatraemia
- Chronic hypernatraemia (present > 5 days) is often well tolerated because of cerebral compensation.
- The child may appear sicker than expected for the clinical signs of dehydration that are present.
- Shock occurs late because intravascular volume is relatively preserved.
- Look for signs of intracellular dehydration and neurological dysfunction:
- Lethargy
- Irritability
- Skin feels “doughy”
- Ataxia, tremor
- Hyperreflexia, Seizures, reduced GCS
Why we cannot reduce hypernatraemia too quickly?
Too rapid reduction of the sodium in hypernatraemia can cause cerebral oedema, convulsions and permanent brain injury
Management of hypernatraemia
- Aim to lower the serum sodium slowly at a rate of no more than 12mmol/L in 24 hours, (0.5mmol/L/hour).
even slower rate will be required for children with chronic hypernatraemia
- Monitor fluid status (urine output, repeat weight (initially 6 hourly, esp if infants or severe hypernatraemia).
- Monitor other electrolytes and blood sugar
- Measure ongoing losses (ie: vomiting or diarrhoea, excluding urine) and replace ml for ml with normal saline
- neurological monitoring
Hyponatraemia
- cause
- diagnosis
Hyponatraemia
- caused by water excess or sodium depletion
- Sodium depletion, renal loss (patient often hypovolaemic)
- diuretics: thiazides, loop diuretics
- Urinary sodium and osmolarity levels aid making a diagnosis
What is the value for Dx of hyponatraemia?
Urinary sodium > 20 mmol/l
What’s the danger with hyponatraemia Mx?
Central pontine myelinolysis
- demyelination syndrome caused by rapid correction of chronic hyponatraemia
- may lead to quadriparesis and bulbar palsy
- diagnosis: MRI brain
Mx of hyponatraemia (algorithm)
Emergency Mx of hyponatraemia
What is SIADH characterised by?
The syndrome of inappropriate ADH secretion (SIADH)
characterised by hyponatraemia secondary to the dilutional effects of excessive water retention
Symptoms and signs of SIADH (hyponatraemia)
- Dehydration
- Headache
- Nausea
- Vomiting
- Tremor and muscle cramps
- Cerebral oedema -confusion, mood swing, and hallucination
- If that continues to get low then the patient can present with seizures, coma and death
Mx of SIADH
Management
- correction must be done slowly to avoid precipitating central pontine myelinolysis
- fluid restriction
- demeclocycline: reduces the responsiveness of the collecting tubule cells to ADH
- ADH (vasopressin) receptor antagonists have been developed
Causes of SIADH
Ix results (electrolytes) in SIADH
- Low blood sodium
- Low osmolality
- Combined with high urine sodium and high urine osmolality
Basic pathophysiology of Osteomalacia
- normal bony tissue but decreased mineral content
- rickets if when growing
- osteomalacia if after epiphysis fusion
Causes of osteomalacia
Types
- vitamin D deficiency e.g. malabsorption, lack of sunlight, diet
- renal failure
- drug induced e.g. anticonvulsants
- vitamin D resistant; inherited
- liver disease, e.g. cirrhosis
Features (clinical) of osteomalacia
- ickets: knock-knee, bow leg, features of hypocalcaemia
- osteomalacia: bone pain, fractures, muscle tenderness, proximal myopathy
Ix in Osteomalacia
Investigation
- low 25(OH) vitamin D
- raised ALP
- low calcium, phosphate (in 30% pts)
- x-ray: children - cupped, ragged metaphyseal surfaces; adults - translucent bands (Looser’s zones or pseudofractures)
Treatment of osteomalacia
Treatment
- calcium with vitamin D tablets
Basic pathophysiology and definition of osteoporosis
- loss of bone mass
- presence of bone mineral density of less than 2.5 standard deviations below the young adult mean density
Risk factors for development of osteoporosis
The major risk factors for osteoporosis are age and female gender.
Other risk factors include:
- corticosteroid use
- smoking
- alcohol
- low body mass index
- family history
What’s the screening tool for osteoporosis?
FRAX or QFracture to assess the 10-year risk of a patient developing a fragility fracture
What’s DEXA scan is used for?
- To assess the actual bone mineral density a dual-energy X-ray absorptiometry (DEXA) scan is used
- The DEXA scan looks at the hip and lumbar spine
- If either have a T score of < -2.5 then treatment is recommended
1st line treatment for osteoporosis
oral bisphosphonate such as alendronate
Other treatments are available but the vast majority of patients are managed with this therapy
Basic pathophysiology of Paget’s disease
Paget’s disease
- increased but uncontrolled bone turnover
- a disorder of osteoclasts -> excessive osteoclastic resorption followed by increased osteoblastic activity
What bones are commonly affected by Paget’s?
The skull, spine/pelvis, and long bones of the lower extremities
Risk factors for Paget’s
Predisposing factors
- increasing age
- male sex
- northern latitude
- family history
Presentation (clinical) of Paget’s
Clinical features - only 5% of patients are symptomatic
- the stereotypical presentation is an older male with bone pain and an isolated raised ALP
- bone pain (e.g. pelvis, lumbar spine, femur)
- classical, untreated features: bowing of tibia, bossing of skull
- raised alkaline phosphatase (ALP) - calcium* and phosphate are typically normal
- skull x-ray: thickened vault, osteoporosis circumscripta
Stereotypical presentation of Paget’s
an older male with bone pain and an isolated raised ALP
Treatment of Paget’s
- bisphosphonate (either oral risedronate or IV zoledronate)
- calcitonin is less commonly used now
Complications of Paget’s
Complications
- deafness (cranial nerve entrapment)
- bone sarcoma (1% if affected for > 10 years)
- fractures
- skull thickening
- high-output cardiac failure
What’s the diagnosis?
Paget’s disease
- marked thickening of the calvarium.
- ill-defined sclerotic and lucent areas throughout
What’s the diagnosis?
Paget’s disease
Isotope bone scan from a patient with Paget’s disease showing a typical distribution in the spine, asymmetrical pelvic disease and proximal long bones.
What’s the diagnosis?
Pelvic x-ray from an elderly man with Paget’s disease
- a smooth cortical expansion of the left hemipelvic bones
- diffuse increased bone density and coarsening of trabeculae
