Diabetes insipidus
- Created by: MazzaW
- Created on: 18-11-19 17:23
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- Diabetes insipidus
- Patho-physiology
- lack of ADH from posterior pituitary
- May be idiopathic
- Common following neurosurgical procedures in and around pituitary fossa
- Symptoms
- Polyuria (>3L/day)
- dilute urine
- Thirst
- Polydipsia
- May lead to dehydration and hyper-natraemia
- Polyuria (>3L/day)
- Investigations
- Rule out other causes of polyuria and polydipsia
- glucose
- post-obstructive diuresis
- diuretics
- calcium
- potassium
- early morning urine osmolality with nothing to drink since midnight
- if urine is concentrated, DI unlikely
- Hypertonic saline copeptin stimulation testing
- Should stimulate ADH production
- Copeptin is a surrogate marker for ADH secretion
- Stable in blood for 24hrs so easier to measure than ADH
- Copeptin is a surrogate marker for ADH secretion
- Infuse 5% saline at 0.06mL/kg/ min for 2hrs
- Usually need 0.5-1L
- Take serum copeptin and osmolality every 30 mins
- Baseline copeptin differentiates between nephrogenic DI and other
- Nephrogenic: high baseline copeptin
- Stimulated copeptin differentiates between central DI and primary polydipsia
- Central: low stimulated copeptin
- PP: high stimulated copeptin
- Should stimulate ADH production
- Rule out other causes of polyuria and polydipsia
- Mgmt
- Desmopressin
- ADH analogue
- Longer half life than ADH
- PO/nasal/SC administration
- Monitor serum sodium and osmolality
- Aim for normal sodium
- Desmopressin
- Patho-physiology
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