SAQ 128 – Metabolic – severe hypernatraemia after seizure

Review Completed

Marked out of 10.00

An 87 year old man from a nursing home presents following a generalised seizure.

His observations are: BP 120/70 mmHg, HR 100 bpm, temperature 36.8 C, oxygen saturation 97% room air, GCS 12 (E4, V3, M5).

Initial blood results are shown below.

Test	Result	Units	Reference range
Na+	183	mmol/L	135-145
K+	4.9	mmol/L	3.2-4.3
Cl-	137	mmol/L	99-109
HCO3-	25	mmol/L	21-28
Urea	23.5	mmol/L	2.7-8.0
Creatinine	105	micromol/L	50-100
Glucose	6.9	mmol/L	3.0-6.0
PO4	2.41	mmol/L	0.65-1.45
Ca2+	2.39	mmol/L	2.0-2.55
Mg2+	1.12	mmol/L	0.70-0.95

Provide two (2) calculations to help you to interpret these results.

(Marked out of 2.0)

/ 2

What is the likely cause for this clinical picture?

(Marked out of 2.0)

/ 2

Complete the following table demonstrating three (3) key treatment tasks and state how you would achieve each of these.

(Marked out of 6.0)

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Total Score: 0 / 10

Percentage: 0%

Key treatment task	How will you achieve the task?
Replace fluid / reduce sodium	Water deficit = 0.6 x premorbid weight x (serum Na – 140) / 140. Replace water deficit with 5% dextrose over 24-48 hours, aiming for sodium fall 0.5 mmol/hr or <10-15 mmol/24 hrs; check sodium regularly and adjust treatment. Add maintenance and ongoing losses.
Treat underlying cause	Treat infection or other cause as guided by history, examination, and further investigations. If central diabetes insipidus, consider ADH supplementation such as desmopressin 1-2 mcg IV/day once euvolaemic.
Discuss goals and ceilings of treatment	Discuss with family because high morbidity and mortality are expected; review pre-existing advance care directions and premorbid quality of life.