23. Polyuria Flashcards
What are Dx of polyuria?
Diabetes Mellitus Diuretics (e.g. diuretic meds., caffeine, alcohol, lithium) Heart Failure Hypercalcaemia Hyperthyroidism Primary Polydipsia Hypokalaemia Diabetes Insipidus
What questions will help you narrow down the cause of polyuria?
What is the temporal pattern of urine output?
Fatigue, weight loss, recurrent infections? (diabetes)
LUTS? frequency, urgency, hesitance, terminal dribbling, incomplete voiding
Pain, frequency, colour, smell? UTI
What will you ask about on PMH of polyuria?
History of renal problems or triggers of renal problems? vasculitides, urinary retention, hypertension
Older patients: ask about cancer + known bony involvement
Any psychiatric disorders
Drug history in polyuria
Diuretics
Lithium (causes nephrogenic DI)
Family history in polyuria
Diabetes
Any cancers
What are simple tests in someone with polyuria?
Capillary blood glucose
Urinalysis
What are further Ix for polyuria?
Fasting glucose Urine osmolality, Electrolytes (primary polydypsia will have hypOnatremia) Urea Creatinine EGFR Calcium TFTs
How do you differentiate between the 2 types of diabetes insipidus them?
Water deprivation test + give desmopressin.
After DDAVP:
Normal urine osmolality: cranial
Low urine osmolality: nephrogenic
What are causes of cranial DI?
Pituitary tumours Cranipharyngiomas Trauma Mets Vascular lesions Meningitis
What is management of cranial DI?
Adequate fluid intake
Investigate cause
Give ADH replacement
What is polyuria?
Passing abnormally large volumes of clear urine
What can cause nephrogenic diabetes insipidus?
Chronic renal failure Hypercalcaemia (bone mets.) Hypokalemia Drugs e.g. Litium Pyelonephritis Hydronephrosis Inherited
What is the difference between cranial and nephrogenic diabetes insipidus?
Cranial: Reduced/ absent secretion of ADH
Nephrogenic: ADH insensitivity
What is primary polydipsia? What group of patients is it more common in?
Psychogenic polydipsia: excessive volitional water intake
Those with a hx psychiatric disorders
