HY USMLE Q#19 ENDO Step 1

​

HY USMLE Q#19 ( Endocrinology step 1 and step 2CK inspired from MEHLMAN instagram) 

A 17-year-old girl goes to the doctor with a 6-month history of low mood and menstrual irregularities. She has gained 13 pounds over the last 6 months. Her heart rate is 53 beats/min. What is likely to be seen in this patient ? 

A. Antibodies against TSH receptors 
B. Anti-mitochondrial antibodies 
C. Decrease serum thyrotropin
D. Granulomas 
E. Increased serum CK

​
​
​
​
✅ Correct answer = increase Serum CK. 
Education Objective:
This patient has hypothyroidism causing an increase in CK. 
The thyroid is needed for muscle metabolism as it regulates mitochondrial oxidative phosphorylation and glycogenolysis. We have reduced ATP—> impaired muscle contraction and relaxation, hence increasing CK. 
There can be increased transaminases and low sodium. 
Hypothyroid myopathy leads to muscle injury, which raises AST (more in muscle) and sometimes ALT.

Also, hypothyroidism lowers cardiac output and renal perfusion leading to increased ADH which lowers sodium levels. 

❌ Choice A: antibodies against TSH receptors aka TSI  are seen in Graves' disease 
❌ Choice B: Anti-mitochondrial AB are seen in primary biliary cirrhosis. 
❌ Choice C: Thyro = shield 
Tropin = turning, changing, or influencing means to stimulate or to act upon. Thyrotropin is also known as thyroid-stimulating hormone would be increased in Hashimoto and not decreased. 
❌ Choice D: Granulomas are seen in a painful and  tender thyroid gland seen in subacute dequverian granulomatous thyroiditis