Andrea M. Harvey, BVSc, DSAM(Feline), DECVIM-CA, MRCVS
Case 1
A 12-year-old male neutered domestic shorthaired cat presented with a history of recent weight loss and polyphagia. He was diagnosed with hyperthyroidism (thyroxine 220 nmol/l; ref. range 15-40 nmol/l) and treatment with methimazole was initiated. After 3 weeks the cat was euthyroid and a bilateral thyroidectomy was performed. A few days following the thyroidectomy the cat presents with facial pruritus and twitching. On examination the cat was quiet with muscle twitching. He was in relatively poor body condition and weighed 3.1 kg. A moderate tachycardia (heart rate 240 bpm) and tachypnoea (respiratory rate 48 breaths per minute) were present. Physical examination was otherwise unremarkable.
What is Your Problem List and Differential Diagnoses?
Blood is collected for routine haematology and serum biochemistry, and urine for routine urinalysis. Results are shown in Figures 1-3. Thyroxine concentration was also re-evaluated at this stage and was 102 nmol/l (ref. range 15-40 nmol/l).
What laboratory abnormalities are present and what are your differential diagnoses for those abnormalities?
Which abnormality is of most immediate concern and how would you manage it?
What are the possible reasons for the persistently high thyroxine concentration?
What are the options for further investigation and management of this case?
Figure 1. Haematology results case 1.
|
|
Value |
Ref. range |
|
Hb |
10.1 g/dl |
8-15 g/dl |
|
HCT |
33.7% |
25-45% |
|
RBC |
7.78 x 1012/l |
5.5-10 x 1012/l |
|
MCV |
43.3 fl |
40-55 fl |
|
MCH |
13 pg |
12.5-17 pg |
|
MCHC |
30.1 g/dl |
30-35 g/dl |
|
Plt |
452 x 109/l |
200-700 x 109/l |
|
WBC |
12.86 x 109/l |
4.9-19 x 109/l |
|
Neutrophils |
11.2 x 109/l |
2.4-12.5 x 109/l |
|
Lymphocytes |
1.04 x 109/l |
1.4-6 x 109/l |
|
Monocytes |
0.62 x 109/l |
0.1-0.7 x 109/l |
|
Eosinophils |
0 |
0.1-1.6 x 109/l |
|
Basophils |
0 |
0-0.1 x 109/l |
Figure 2.Biochemistry results case 1.
|
|
Value |
Ref. range |
|
Urea |
13.2 mmol/l |
6.5-10.5 mmol/l |
|
Creatinine |
95 µmol/l |
70-175 µmol/l |
|
Total protein |
51.8 g/l |
65-91 g/l |
|
Albumin |
23.6 g/l |
24-35 g/l |
|
Globulin |
28.2 g/l |
21-51 g/l |
|
AG ratio |
0.84 |
0.4-1.3 |
|
ALT |
113 IU/l |
15-45 IU/l |
|
ALP |
97 IU/l |
15-60 IU/l |
|
Glucose |
4.2 mmol/l |
3.5-5 mmol/l |
|
Creatine kinase |
8802 IU/l |
50-150 IU/l |
|
Bilirubin |
3.8 µmol/l |
0-10 µmol/l |
|
Sodium |
157.6 mmol/l |
149-157 mmol/l |
|
Potassium |
4.2 |
4-5 mmol/l |
|
Chloride |
116 |
115-130 mmol/l |
|
Calcium |
1.16 |
2.3-2.5 mmol/l |
|
Ionised calcium |
0.6 |
1.1-1.4 mmol/l |
|
Phosphate |
2.5 |
0.95-1.55 mmol/l |
|
Fasting bile acids |
9.6 |
0-20 µmol/l |
Figure 3. Urinalysis results case 1.
|
Parameter |
Result |
|
pH |
7.1 |
|
Blood |
Negative |
|
Glucose |
Negative |
|
Ketones |
Negative |
|
Protein |
58.4 mg/dl |
|
Bilirubin |
- |
|
Specific gravity |
1. 030 |
Case 2
A 10-year-old female neutered Burmilla presents with a few days history of weakness, with intermittent inability to jump and a wobbly gait. No other clinical signs have been noted. At the time of presentation however she is clinically normal with no apparent weakness evident. The cat was in good body condition and weighed 4.12 kg. Physical examination was unremarkable. Systolic blood pressure is measured and found to be 180 mmHg.
What is your interpretation of this blood pressure measurement?
What else could be done to investigate the possibility of hypertension?
List differential diagnoses for hypertension
Blood is collected for routine haematology, serum biochemistry and urinalysis. Results are shown in Figures 4-6.
What is the most significant laboratory abnormality?
List differential diagnoses for this abnormality How would you treat this cat in the short-term?
How could you further investigate this case? Can the hypertension and hypokalaemia be linked together?
Figure 4. Haematology results case 2.
|
|
Value |
Ref. range |
|
Hb |
13.3 g/dl |
8-15 g/dl |
|
HCT |
42.8% |
25-45% |
|
RBC |
8.72 x 1012/l |
5.5-10 x 1012/l |
|
MCV |
49.0 fl |
40-55 fl |
|
MCH |
15.2 pg |
12.5-17 pg |
|
MCHC |
31.0 g/dl |
30-35 g/dl |
|
Plt |
92 x 109/l |
200-700 x 109/l |
|
WBC |
11.7 x 109/l |
4.9-19 x 109/l |
|
Neutrophils |
9.36 x 109/l |
2.4-12.5 x 109/l |
|
Lymphocytes |
1.76 x 109/l |
1.4-6 x 109/l |
|
Monocytes |
0.59 x 109/l |
0.1-0.7 x 109/l |
|
Eosinophils |
0 |
0.1-1.6 x 109/l |
|
Basophils |
0 |
0-0.1 x 109/l |
|
Smear comment: |
Platelets appear clumped on film,
platelet count may be falsely low, platelets plentiful |
Figure 5. Biochemistry results case 2.
|
|
Value |
Ref. range |
|
Urea |
10.5 mmol/l |
6.5-10.5 mmol/l |
|
Creatinine |
139 µmol/l |
70-175 µmol/l |
|
Total protein |
87.1 g/l |
65-91 g/l |
|
Albumin |
32.9 g/l |
24-35 g/l |
|
Globulin |
52.2 g/l |
21-51 g/l |
|
AG ratio |
0.61 |
0.4-1.3 |
|
ALT |
48 IU/l |
15-45 IU/l |
|
ALP |
42 IU/l |
15-60 IU/l |
|
Glucose |
4.2 mmol/l |
3.5-5 mmol/l |
|
Creatine kinase |
837 IU/l |
50-150 IU/l |
|
Sodium |
149.1 mmol/l |
149-157 mmol/l |
|
Potassium |
2.96 mmol/l |
4-5 mmol/l |
|
Chloride |
113 mmol/ l |
115-130 mmol/l |
|
Calcium |
2.56 mmol/l |
2.3-2.5 mmol/l |
|
Phosphate |
1.1 mmol/l |
0.95-1.55 mmol/l |
Figure 6. Urinalysis results case 2.
|
Parameter |
Result |
|
pH |
7.1 |
|
Blood |
Negative |
|
Glucose |
Negative |
|
Ketones |
Negative |
|
Protein |
11.1 mg/dl |
|
Bilirubin |
- |
|
Specific gravity |
1.024 |