Credits

• Section Writer: Dr. Om J Lakhani
• Section Editor: Dr. Om J Lakhani

Q. What is Telogen?

• Telogen phase is when there is the resting phase in the hair growth cycle

Q. What is Telogen effluvium ?

• It is one of the most common causes of hair loss
• It is generally temporary
• It is caused by any illness or major physiological stress
• Any stress produces the hair to go in a resting phase and hair growth ceases temporarily to conserve the energy
• If this is prolonged, then the hair loss soon becomes apparent
• Such hair loss is transient and often recovers after the underlying illness is corrected
• Hair loss associated with thyroid dysfunction is often due to Telogen effluvium

Q. What produces hair loss- hypothyroidism or hyperthyroidism?

• Both hyper and hypothyroidism can cause hair loss

Q. What is the pattern of hair loss with thyroid disorders?

• Hair loss is generally diffuse

Q. Enlist the patterns of hair loss that may be seen with hypothyroidism?

• A study done on this topic by Vincent et al show that the following are the patterns of hair loss seen in hypothyroid patients ^[1]
  • diffuse alopecia - most common - 70%
  • alopecia areata - 11%
  • androgenetic alopecia- 14%
  • cicatricial alopecia- 0.32%
  • alopecia totalis- 0.16%
  • alopecia Universalis- 0.41%
  • madarosis-
  • diminished facial hair- 0.57%
  • diminished body hair- 0.16%

Q. Does Subclinical hypothyroidism produce hair loss?

• Subclinical hypothyroidism is unlikely to cause hair loss
• This is a common misbelief and often a cause of referral to an endocrinologist

Q. Does the hair loss worsen after hypothyroidism is treated with levothyroxine therapy?

• Yes
• There is a transient worsening of hair loss with hypothyroidism treatment initially
• In such cases, paradoxically the hair loss may follow the treatment for the thyroid and the thyroid medication may be erroneously blamed, leading to the withdrawal of treatment, which in turn may worsen the hair loss.
• This occurs because of correction of hypothyroidism within the first month of therapy
• This is because the resting hair follicle becomes active again and is shed rapidly
• The new hair that grows, however, is healthy and in due course, the hair growth improves

Q. Does radioactive iodine therapy for Graves' disease produce hair loss?

• No
• RAIT does not cause hair loss

Q. Do Antithyroid drugs used in Graves' disease produce hair loss?

• Yes
• Carbimazole, PTU causes hair loss on its own

Q. What is alopecia areata and what is its link with hypothyroidism?

• Alopecia areata is sudden hair loss that starts with one or more circular bald patches that may overlap.
• It is more common in children
• alopecia areata likely has autoimmune etiology and the presence of overt hypothyroidism may have a potential link since it is most often autoimmune

Q. Does the treatment of hypothyroidism improve the outcome in alopecia areata?

• alopecia areata often runs an independent course with hypothyroidism
• However, there is some improvement seen in clinical practice with levothyroxine treatment
• This is most like due to the correction of Telogen effluvium

Q. How do you differentiate hair loss due to alopecia aerta versus that of hypothyroidism if they coexist in the same patient?

• Alopecia produces regional hair loss unlike that due to thyroid which is more diffuse hair loss

Q. Apart from hair loss from the scalp, is there hair loss from other areas in hypothyroidism?

• Thyroid dysfunction can also eyebrow hair loss which often transient and improves with treatment
• Body hair may also be lost
• "Superciliary madarosis" is a classical sign of hypothyroidism taught to medical students. However, it is rarer than we think.

Q. What is a madarosis ?

• Madarosis is defined as the loss or absence of eyelashes (ciliary madarosis) or eyebrows (superciliary madarosis)
• 

Q. What are the issues with hair supplements and thyroid?

• Two issues
  • Some supplements may contain iodine and may cause thyroid dysfunction (Please see Iodine deficiency disorders)
  • Some supplements may have biotin which may interfere with thyroid function

Q. How common is the use of biotin in endocrine test ?

• Atleast 50% of the endocrine tests have biotin in their separation step

Q. Does biotin produce false high or false low ?

• Can cause both depending on the situation
• False low
  • Large molecules with noncompetitive IMA method
    • C-peptide
    • FSH
    • TSH
    • Prolactin
• False high
  • Small molecules with competitive assay
    • Progesterone
    • Steroid hormones
    • T3, T4

#Clinicalpearl- Since biotin produces false high for t3 and t4 and false low for TSH, wrong diagnosis of Graves' disease is often seen

Q. Where is high dose biotin used in practice ?

• Dermatology- Hair and Nail things
• Neurology- Multiple sclerosis

Q. What dose of biotin is likely to cause assay interference ?

• Biotin dose >5 mg/day is likely to cause assay interference

Q. How long should biotin be stopped before repeating the test ?

• Stop for atleast 2-3 days
• Since it is renal excreated- longer perior for patients with impaired renal function

Q. What can labs do to check for biotin interference ?

• Use streptavidin beads or other approaches to look for biotin interference

Q. Which other antibody will produce a picture similar to biotin interference ?

• Presence of streptavidin antibody will produce a similar picture as biotin interference

Q. Do parathyroid conditions also produce hair loss?

• Yes
• Parathyroid conditions also produce hair loss

Q. Does central hypothyroidism produce hair loss?

• Yes
• In female is produces androgenetic alopecia

Q. What are the other prominent skin findings associated with hypothyroidism?

• Vitiligo
• Urticaria

#Real-life-cases

• Case capsule
  • 10-year-old child presents to the dermatology clinic with patchy alopecia.
  • This is alopecia areata
  • Dermatologist orders a thyroid function test
  • The child is found to have Overt hypothyroidism
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