Endocrinology Flashcards
Why is an insulin stress test used to diagnose hypopituitrarism
It stimulated the HPA axis.
IV insulin will result in Hyoglycaemia
This in turn shoul stimualte the pituitary to secreate ACTH
ACTH will act at the level of the adrenal glands to secrete cortisol
Cortisol levels can be measures
How would you investigate hypopituitarism
Insulin stress test
C/I of an insulin stress test
Adrenal insufficiency
Ischaemic Heart disease
Epilepsy
1st line investigation for addisons disease
short synacthen test and 09 00 am Cortisol levels
What is the main medication used to treat gastric paresis
Metoclopramide - Prokinetic effect
Domperidone and erythromycin - Also prokinetic
How would you categorise diabetic neuropathy
Peripheral neuropathy vs Autonomic Neuropathy
How does Diabetic peripheral neuropathy present
Sensory loss in a glove and stocking manner (Affecting the lower legs first due to the length of the sensory neurons)
- Can be painful
How would you treat peripheral neuropathy in diabetes
Same as any painful neuropathy
1st line - Amtriptylline, Duloxetine, pregabaline or Gabapentin
- Tramadol can be used as rescue therapy
What are the 3 forms of autonomic diabetic neuropathy
1) Gastric paresis
2) Chronic diarrhoea
3) GORD - Reduced tone fo the LES
Symptoms of gastric paresis
Vomiting
Bloating
Erratic Blood glucose levels
How can you diagnose Hashimoto’s thyroiditis
Raised Anti-Tyroid peroxidase antibody titre + Low T4 and Riased TSH
Rx for Hashimotos thyroiditis
Levothyroxine
Why is the waterdeprivation test used
To deliniate the cause of polydypsia (Excessive drinking/thirst)C
Causes of polydipsia
1) Psychogenic (Seen in schizophrenia)
2) Cranial Diabetes Insipidus (Trauma, Infections)
3) Nephrogenic DI
Causes of nephrogenic DI
Genetic - 85%
- Mainly V2R MUTATION - X-linked - 90%
- Can also be AQP2 Gene mutation - 10%
Acquired: 15%
- CKD
- Hypercalcaemia
- Hypokalaemia
- Iatrogenic - Lithium
How is the water deprivation test carried out
Initial measurement of plasma Osmolality
- Psychogenic - Low
- Crania DI - High
- Nephrogenic - High
Water deprivation for 8 hours then measure Urine Osmolality
- Psychogenic - >400
- Cranial DI - <300
- Nephrogenic - <300mOsm
After DDAVP admin - Urine Osmolality
- Psychogenic - >400
- Cranila DI - >800
- Nephrogenic - <300
What is the difference between hyponatraemia seen in SIADH vs DI Vs psychogenic polydypsia
SIADH - Euvolaemic Hyponatraemia due to increased ADH secretion
DI - Hypovolaemic Hypernatraemia due to either reduced ADH secretion (Cranial) or defective at the nephrons
Psychogenic Polydipsia - Hypervolaemic Hyponatraemia
Mechanism of action of Metformin
AMPK activation - Increases insulin sensitvity
Adverse effects of metformin
GI upset - Nausea, anorexia, Diarrhoea
Lactic acidosis - After MI, AKI, Sepsis
Contraindications to metformin
CKD - eGFR <30
Acute episodes of hypoperfusion due to increased risk of lactic acidosis
