Pathophysiology of myopathy caused during hypothyroidism and hyperthyroidism

Hello awesomites! Today's topic of discussion is - Myopathy in thyroid disease.

Interestingly, it is caused by both, hypothyroidism as well as hyperthyroidism.

What is myopathy?

It is a disease of muscle tissue where, ultimately, muscles get weak and are unable to perform work due to deficiency of ATP.

Why is there myopathy in hyperthyroidism?

The thyroid hormone is a catabolic hormone. Hyperthyroidism increases energy expenditure, glucose turnover, lipolysis, and protein breakdown (proteolysis). But here is the catch - Hyperthyroidism increases whole-body protein turnover and breakdown before any measurable changes in energy expenditure or glucose and fat metabolism, suggesting that amino acid and protein metabolism is an early and primary target for thyroid hormone action in humans. It was therefore concluded that the thyroid-hormone concentration may be an important factor in regulating muscle proteolysis. The altered protein metabolism causes myopathy.

Then, one may ask, why myopathy in hypothyroidism? Less thyroid hormone should lead to less protein breakdown, shouldn't it?

Well, this is a good question! Slightly complex and tricky to answer though. 

In hypothyroidism, there is abnormal glycogenolysis, defective mitochondrial oxidative metabolism and triglyceride storage.

Abnormal glycogenolysis and triglyceride storage: Less glucose is released and utilised because of this. The body starts using more proteins usually derived from muscles leading to myopathy.

Mitochondrial oxidative metabolism defect: Thyroid hormone is responsible for activation of bc1 complex also known as complex 3 & succinate dehydrogenase. Less activation of bc1 leads to less formation of ATP from glucose.... So again, the body switches to proteins from muscles as a source of energy!

That's all!
Stay cool :)

~Ojas

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Which genre or type of music do you like the most? Well, it surely has to do a lot with the functioning of our brain. Some of you may like slow music while others like to rock n roll on the floor while listening to their favourite beats. I am more of the latter type too, depending on the mood. ;p

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This is a fun and concise post on the pharmacology of TCAs. Excited? :D

Fact of the day: Green - The colour of medicine

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Why?

Fact of the day: Paradoxical undressing in fatal hypothermia

Hypothermia causes paradoxical undressing.

This typically occurs during moderate to severe hypothermia, as the person becomes disoriented, confused, and combative. They may begin discarding their clothing, which, in turn, increases the rate of heat loss. It is estimated that twenty to fifty percent of hypothermia related deaths are due to paradoxical undressing.

Why does this happen?

Fact of the day: Psychosomatic symptoms love to travel

Hey Awesomites

Yes, you read it right. The symptoms of psychosomatic disorders flit from one body part to another, and just too easily and quickly ( they love to travel a lot ;p ) . Just as one symptom is discovered, it disappears and another one emerges in some other part of the body.

The psychosomatic symptoms have been linked to a chameleon. Every time a medicine tries to pin them down,  they become something different.

That's all
- Jaskunwar Singh

The colours of a chameleon are not more numerous and inconstant than the varieties of the hypochondriac and hysteric disease.
 - Robert Whytt

NYHA Classification Mnemonic

Hey guys, this post will help you to remember the definitions of the four NYHA classes.

So first just remember two phrases-
"Patient with a heart disease" and "in ordinary or accustomed activities". For convenience I will use letters A and B to refer to these phrases respectively. Now I will just fill in the gap between them.

1. NYHA Class I:
A--- will not get dyspnea ---B.

2. NYHA Class II:
A--- will get dyspnea ---B.

3. NYHA Class III:
A--- will get dyspnea in less than ---B.

4. NYHA Class IV:
A--- will get dyspnea at rest.

This system of classification has its flaws since the definition of "ordinary and accustomed activities" is entirely subjective. Like for example if a rich businessman gets breathless after walking 1 km, you may label him as NYHA Class II, but the same case in a hard working labourer will have to be labelled as NYHA Class III.

And another thing that NYHA has recently clarified NYHA Class III a bit further, it has included self-care activities in it's spectrum. As a supposition, if a 56 year old male person gets breathless while shaving or bathing then it is NYHA Class III.

-VM

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Grave's ophthalmopathy features mnemonic

Hey Awesomites

Grave's disease, a common cause of primary hyperthyroidism causes some epic features of ophthalmopathy apart from lid retraction and lid lag. Mnemonic: EPIC

E- Exophthalmos
P- Periorbital Edema
I- Involvement of ocular muscles (diplopia)
C- Conjunctival irritation and chemosis

- Jaskunwar Singh

Amiodarone- induced thyroid dysfunctions

Hello

Amiodarone, a potent class III anti- arrhythmic drug is contraindicated in thyroid patients or those with subclinical disease. The reason lies in the pharmacokinetic profile of this drug.

The drug has a structural resemblance to triiodothyronine (T3) and thyroxine (T4). In the body, it is metabolized by dealkylation to Desethylamiodarone (DEA), the intrathyroidal concentration of which is higher than the parent drug.

Normal daily recommended intake of iodine for adults is approx. 0.15mg (150mcg).  Each 200mg tablet of amiodarone contains about 74.4mg of iodine with 7.4mg (10%) being released as free form. This is roughly 50- fold higher than the normal. Therefore, total body stores may remain increased for upto 9 months after stopping the drug.

High iodine content of this drug inhibits  local type-1 5'- deiodinase activity (blocking conversion of T4 to T3) and type- II 5'- deiodinase activity in the pituitary. As a result, TSH is increased initially (mild elevation) and then return to normal or may even decrease in euthyroid patients after weeks, while T4 is normal or raised, and T3 levels decrease.

The increased delivery and uptake of iodine by the thyroid gland may cause increase in hormone production and release, a condition called type-1 Amiodarone- induced thyrotoxicosis (AIT) . In other cases, excessive thyroid tissue destruction due to destructive thyroiditis may lead to type-2 Amiodarone- induced thyrotoxicosis. These are hyperthyroid states!!
Discontinuation of the drug is recommended, if not, then high doses of thioamides and corticosteroids may work in AITs.

Amiodarone may also cause hypothyroidism (AIH) in  patients depending upon the iodine status of individuals and prior thyroid disease. Wolff- chaikoff effect is shown by thyroid cells due to failure of thyroid hormonogenesis. Levothyroxine is the drug of choice.


Thats all
- Jaskunwar Singh

Fact of the day: Burning the heart to ashes

An interesting fact about heart I read today:

The heart is resilient, literally. When a body is burnt, the heart is the last organ to oxidize. While the rest of the body can catch flame like a polyester sheet on campfire, it takes hours to burn the heart to ash because it's deep inside!

That's all!

Did you know? According to Hindu mythology, when Arjuna cremated the body of Lord Krishna, his whole body turned into ashes, except his heart which was still burning. Arjuna washed the ashes and burning heart into the river.

- Jaskunwar Singh

Munchausen's syndrome

Hello

"Psychosomatic disorders are conditions in which a person suffers from significant physical symptoms (causing real distress and disability), that is out of proportion to that which can be explained by medical tests and physical examinations."

Karl Friedrich Von Munchausen, the "Baron of Lies" gave his name to the syndrome. Munchausen's syndrome (now more correctly called factitious disorder in DSM- 5 classification of somatic symptom and related disorders ) refers to patients who imitate illness (may be in an exaggerated form ) for medical attention and care and may even expose themselves to life- threatening operations, amputations, unnecessary medications and toxic treatments.

Lets take an example: A woman presents to hospital with a headache and a dilated pupil. On investigations, scans were normal and no other systemic abnormality seen. Then, a nurse walks into her room and finds the patient self- administering dilating eye drops into the affected eye.

The person has an awareness of the lies they are telling but they surely do it to seek medical care and attention, being unaware of their own motivation and uncontrolled behavior.

Upto one- third of patients in neurology ward suffer from psychosomatic illness and most often, an emotional cause is suspected.


Thats all
- Jaskunwar Singh

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