A 75 year old man is brought to the Emergency Department by his family. He lives alone and has mild cognitive impairment. He has a past medical history of atrial fibrillation for which he is prescribed digoxin. In a confused state he has taken multiple digoxin tablets, he cannot be certain how many. Which of the following is an indication for digoxin-specific antibody (Fab) fragments in digoxin toxicity?
The therapeutic concentration of digoxin is 1 - 2 microgram/L. Plasma digoxin concentrations do not correlate well with features of toxicity in poisoning. Signs and symptoms of digoxin toxicity become more frequent with plasma concentrations above 2 microgram/L. Severe toxic effects may be seen with digoxin concentrations greater than 4 microgram/L.
The effects of digoxin may be potentiated by co-ingestion of a number of medications, including quinidine, erythromycin, verapamil, diltiazem and amiodarone. Electrolyte disturbance (hypokalaemia, hypercalcaemia, hypomagnesaemia) may also predispose the patient to digitalis toxicity.
Poor prognostic factors include: age over 55 years, male, underlying heart disease, high degree atrioventricular block, and hyperkalaemia.
N.B. Onset of features in toxicity from chronic therapy can be very variable, but is often preceded by dehydration from other causes or drug interactions. While hyperkalaemia is a useful marker of toxicity in acute overdose, it is less useful in chronic poisoning, as its absence does not indicate lack of toxicity.
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Biochemistry | Normal Value |
---|---|
Sodium | 135 – 145 mmol/l |
Potassium | 3.0 – 4.5 mmol/l |
Urea | 2.5 – 7.5 mmol/l |
Glucose | 3.5 – 5.0 mmol/l |
Creatinine | 35 – 135 μmol/l |
Alanine Aminotransferase (ALT) | 5 – 35 U/l |
Gamma-glutamyl Transferase (GGT) | < 65 U/l |
Alkaline Phosphatase (ALP) | 30 – 135 U/l |
Aspartate Aminotransferase (AST) | < 40 U/l |
Total Protein | 60 – 80 g/l |
Albumin | 35 – 50 g/l |
Globulin | 2.4 – 3.5 g/dl |
Amylase | < 70 U/l |
Total Bilirubin | 3 – 17 μmol/l |
Calcium | 2.1 – 2.5 mmol/l |
Chloride | 95 – 105 mmol/l |
Phosphate | 0.8 – 1.4 mmol/l |
Haematology | Normal Value |
---|---|
Haemoglobin | 11.5 – 16.6 g/dl |
White Blood Cells | 4.0 – 11.0 x 109/l |
Platelets | 150 – 450 x 109/l |
MCV | 80 – 96 fl |
MCHC | 32 – 36 g/dl |
Neutrophils | 2.0 – 7.5 x 109/l |
Lymphocytes | 1.5 – 4.0 x 109/l |
Monocytes | 0.3 – 1.0 x 109/l |
Eosinophils | 0.1 – 0.5 x 109/l |
Basophils | < 0.2 x 109/l |
Reticulocytes | < 2% |
Haematocrit | 0.35 – 0.49 |
Red Cell Distribution Width | 11 – 15% |
Blood Gases | Normal Value |
---|---|
pH | 7.35 – 7.45 |
pO2 | 11 – 14 kPa |
pCO2 | 4.5 – 6.0 kPa |
Base Excess | -2 – +2 mmol/l |
Bicarbonate | 24 – 30 mmol/l |
Lactate | < 2 mmol/l |