A 51 -year-old female presents with a decreased conscious state, Glasgow Coma Scale (GCS) 12, confusion and myoclonus. She is on treatment for a seizure disorder. Her CT brain scan shows no acute intracranial abnormality.
Her investigations are as follows:
Parameter |
Patient Value |
Adult Normal Range |
|
Sodium |
1 38 mmol/L |
135-145 |
|
Potassium |
4.1 mmollL |
3.5 - 5.2 |
|
Bicarbonate |
18 mmol/l_• |
22 - 32 |
|
Urea |
14.2 mmoVL• |
3.0 - 8.0 |
|
Creatinine |
210 mol/l_• |
45 - 90 |
|
Bilirubin |
54 mol/L* |
< 20 |
|
Alanine transferase |
2710 |
< 35 |
|
Aspartate transferase |
1365 |
< 35 |
|
Alkaline phosphatase |
103 Ull- |
30- 110 |
|
Glutam transferase |
67 U/L* |
< 40 |
|
Albumin |
37 |
35-50 |
|
Protein |
61 IL |
60 - 80 |
|
Ammonia |
156 |
< 50 |
|
List possible causes of the hyper-ammonaemia in this patient. (40% marks)
The patient; she is probably on valproate for her seizure disorder. Valproate overdose is a logical explanation for a decreased level of consciousness, myoclonus and high ammonia.
Causes of hyperammonaemia more broadly could be any of the following:
Increased substrate for ammoniagenesis
Bypass of normal metabolism
|
Acquired urea cycle defects
Congenital urea cycle defects
Excess of exogenous ammonia
Reabsorption of excreted ammonia
|
Conway, Edward Joseph, and Robert Cooke. "Blood ammonia." Biochemical Journal 33.4 (1939): 457.
Shambaugh, G. E. "Urea biosynthesis I. The urea cycle and relationships to the citric acid cycle." The American journal of clinical nutrition 30.12 (1977): 2083-2087.
McDermott Jr, William V., Raymond D. Adams, and Athol G. Riddell. "Ammonia metabolism in man." Annals of surgery 140.4 (1954): 539.
Vince, Angela, et al. "Ammonia production by intestinal bacteria." Gut 14.3 (1973): 171-177.
Vince, Angela J., and Sigrid M. Burridge. "Ammonia production by intestinal bacteria: the effects of lactose, lactulose and glucose." Journal of medical microbiology 13.2 (1980): 177-191.
Dohrenwend, Paul, and Richard D. Shih. "Glycine Induced Hyperammonemia After Bladder Rupture During Transurethral Resection of a Bladder Tumor." Journal of Medical Cases 4.4 (2013): 250-253.
Felipo, Vicente, and Roger F. Butterworth. "Neurobiology of ammonia." Progress in neurobiology 67.4 (2002): 259-279.
Hashim, Ibrahim A., and Jennifer A. Cuthbert. "Elevated ammonia concentrations: Potential for pre-analytical and analytical contributing factors." Clinical biochemistry 47.16 (2014): 233-236.
Clay, Alison S., and Bryan E. Hainline. "Hyperammonemia in the ICU." CHEST Journal 132.4 (2007): 1368-1378.
Weng, Te-I., Frank Fuh-Yuan Shih, and Wen-Jone Chen. "Unusual causes of hyperammonemia in the ED." The American journal of emergency medicine 22.2 (2004): 105-107.
Hawkes, N. D., et al. "Non-hepatic hyperammonaemia: an important, potentially reversible cause of encephalopathy." Postgraduate medical journal 77.913 (2001): 717-722.