55
Appendices
†
If strong suspicion of hyperthyroidism still exists,
consider retesting in 4–6 weeks or a technetium scan.
CBC = Complete blood count
Note:
1 µg/dL is equal to 12.87 nmol/L. A result that
falls within the gray zone of the assay should be
considered ambiguous.
Feline hyperthyroidism suspected
Normal T
4
0.8–4.7 µg/dL
(10.0–30.0 nmol/L)
Low T
4
<0.8 µg/dL
(<10.0 nmol/L)
High T
4
>4.7 µg/dL
(>60.0 nmol/L)
Hyperthyroidism likely
Hyperthyroidism unlikely
†
Euthyroid sick
or iatrogenic
Low or
normal fT
4
High fT
4
Normal T
4
(gray zone)
2.3–4.7 µg/dL
(30.0–60.0 nmol/L)
Common clinical
signs in cats
• Weight loss
• Hyperactivity
• Polyphagia
• Palpable goiter
• Unkempt coat
Initial database
• Total T
4
• CBC
• Chemistry with
electrolytes
• Complete urinalysis
