A 47-year-old, previously well, 70 kg male was admitted to the Emergency Department with agitation and confusion. Following catheterisation, his urine output in the next few hours was 300 — 350 ml/hr. The results of his blood tests are as follows:
Parameter |
Patient Value |
Adult Normal Range |
Sodium |
169 mmol/L* |
135 - 145 |
Potassium |
4.6 mmol/L 105 mmol/L |
|
Chloride |
95 - 105 |
|
Bicarbonate |
26.0 mmol/L |
22.0 - 26.0 |
Glucose |
6.6 mmoI/L* |
|
Urea |
9.6 mmol/L* | |
Creatinine |
115 prnoI/L* |
45 — 90 |
Magnesium |
0.88 mmol/L |
0.75 - 0.95 |
Albumin |
28 g/L* |
35 - 50 |
Protein |
58 g/L* |
60 - 80 |
Plasma osmolality |
360 mmol/kg* |
290 - 310 |
Urine specific gravity |
1.005* |
1 .010 - 1.030 |
a) What is the most likely diagnosis? (10% marks)
b) How would you manage the hypernatremia? (30% marks)
a)
Diabetes Insipidus
b)
Examiner Comments:
Management of diabetes insipidus was handled poorly, as some of the described fluid regimes were considered dangerous
The major abnormalities are:
This is clearly diabetes insipidus. The urine findings and and the low osmolar gap rule out the interference of things like mannitol.
Management of diabetes insipidus consists of two major strategies:
1) Correct the water balance.
2) Interrupt the pathophysiology
Singer, Irwin, James R. Oster, and Lawrence M. Fishman. "The management of diabetes insipidus in adults." Archives of internal medicine 157.12 (1997): 1293-1301.
Libber, Samuel, Harold Harrison, and David Spector. "Treatment of nephrogenic diabetes insipidus with prostaglandin synthesis inhibitors." The Journal of pediatrics108.2 (1986): 305-311.
Knoers, N., and L. A. H. Monnens. "Amiloride-hydrochlorothiazide versus indomethacin-hydrochlorothiazide in the treatment of nephrogenic diabetes insipidus." The Journal of pediatrics 117.3 (1990): 499-502.