Certificate In Clinical Pathology
The biochemistry panel shows a marked glucose elevation of 37.03 mmol/l (reference levels 3.66 –6.31 mmol/l). The biochemistry also shows an increase in ALT at 66 U/l (reference levels 0-55 U/l), GLDH levels
at 17 U/l (reference levels 0-12 U/l), an increase in cholesterol at 9.41 mmol/l (reference levels 3.5-7.0 U/l) and a decrease in sodium levels at 139 mmol/l (reference level 141-152 mmol/l) and potassium at 3.1 mmol/l (3.6-5.35 mmol/l).
The urinalysis shows a moderate glucose reading of 2+ (reference level - negative) and a positive ketone body (reference level –negative), the pH level is 7 which is classed as neutral. The USG reading is 1.042.
The venous blood gas analysis shows a severe metabolic acidosis with a respiratory compensation.
The moderate hyperglycaemia is consistent with a diabetes mellitus (DM) diagnosis, stress hyperglycaemia should always be considered as a differential diagnosis, however it would not be expected to be at such high levels, and it is less commonly seen in canine patients.
A patient suffering from DM would also possibly show glucosuria and ketonuria in a urinalysis evaluation. The moderate hyponatraemia would be related to increased renal sodium excretion in conjunction with the ketonuria.The mild hypokalaemia is most likely caused by an increased renal potassium excretion due to ketonuria, however an increased loss due to vomiting and decreased intake due to anorexia are also possible, although these clinical signs have not been noted in this patient.
Freeman & Kleener (2015) state that hypercholesterolaemia is also described in patients with DM. The other differential for this diagnosis could be cholestasis, but due to normal ALP levels this is unlikely. The ALT and GLDH are mildly increased and indicate a hepatocellular.
All patients have positive and negatively charged ions that regulate electrical impulses, moderate chemical reactions and aid in multiple metabolic functions. Cations are positively charges ions and include sodium (Na) and potassium (K). Anions are negatively charged ions and include Chloride (Cl) and Bi carbonate (HCO3). There are several anions and cations that are not routinely checked, including sulfate, phosphate and lactate. It is these unmeasured anions in a serum sample that form the Anion gap (AG).
Freeman & Kleener (2015) provide the following calculation to work out the AG.
AG is normally measured at 12–24 mmol/l in dogs. Calculation of the AG is useful to detect unmeasured anions leading to metabolic acidosis.
An elevated high ion gap (>35) in the metabolic acidosis patient suggests an addition of an unmeasured charged ion producing the acidosis.
This patient has an increased AG therefore a metabolic acidosis.
Differential diagnosis for this patient may include a foreign substance such as EG intoxication, whereby glycolate and oxalate are formed by the liver and bicarbonate is consumed, leading to metabolicacidosis with increased AG, Freeman & Kleener (2015).
Hypoadrenocorticism, lactate acidosis, renal disease, uraemia or some toxins such as ethanol, paraldehyde, aspirin and ethylene glycol could also be other potential reasons for the increased AG.