Case 13: Which is it – Androgenetic Alopecia or Telogen Effluvium?

GTI is a 23 y/o male complaining of hair loss x 1 year. He states that his hair is coming out more than normal and he sees hair on his brush and in the shower. On gross inspection he has some thinning across the top of his scalp. His hairline is intact.

 
Question 1: Which is the most likely diagnosis?

1. Androgenetic alopecia (AGA).
2. Telogen effluvium (TE).

Answer: A. Androgenetic alopecia. Androgenetic alopecia is extremely common in young men. Telogen effluvium is uncommon. For reasons not well known, men seem much less likely to respond to stress with shedding (TE) than women, in whom this is relatively common. The fact that this patient gives a history of more hair coming out is usually a “red herring” as this often does not imply telogen effluvium. In androgenetic alopecia, the growth cycle shortens, so a bit more hair may be lost than normal, but the pathogenesis of androgenetic alopecia is that the hair does not grow in (at the same fullness), rather than the hair is falling out (as in TE).

 
Question 2: What is the single most important question that you can ask the patient to differentiate between AGA and TE?

1. Which did you notice first – the thinning or the shedding?
2. Have you had increased stress in the past 3-6 months?
3. Do you have a family history of genetic hair loss?

Answer: A. In genetic hair loss, the process of miniaturization causes the hair to progressively diminish in diameter and in length. Therefore, the first thing that a patient usually notices with AGA is either a receding hairline or thinning. Once he notices this, he pays more attention to hair in the tub and hair on the brush and he thinks increased hair “coming out” must be the cause. As we discussed in question #1, with AGA, the problem is that the hair is not growing in. What he notices is either the slight increase in hair loss due to the shortened hair cycle or just that he is paying more attention to the hair that comes out daily in the telogen phase of the normal hair cycle. The questions in answers B and C are important to ask but are less critical to the differential diagnosis.

 
Question 3: To support a diagnosis of AGA, what are the most important questions to ask in the history?

1. Do you have a family history of hair loss?
2. What medications are you currently taking?
3. Any recent major life stressors?
4. Where on the scalp have you noticed the hair loss to occur?

Answer: A, D. Androgenetic alopecia is an inherited trait from both sides of the family. It often begins in a localized pattern rather than one that is diffuse. The latter is more often seen with telogen effluvium. New medications and recent life stressors often indicate a TE-related shed to a stress.

 
Question 4: To support a diagnosis of TE, what are the most important questions to ask in the history (list all that apply)?

1. What medications are you currently taking?
2. Any recent major life stressors?
3. Do you follow a vegetarian diet?
4. Any significant weight loss?

Answer: All the above. All these questions can support a diagnosis of telogen effluvium. Medications, stress, anemia, and weight loss can all cause the hair to enter a resting period during the hair growth cycle. This resting phase is immediately followed by a shed phase and is noticed by the patient 1-3 months after the stress has occurred.

 
Question 5: How would you differentiate between AGA and TE on the physical exam (list the two most useful answers).

1. A positive hair pull test would indicate TE.
2. A negative hair pull test supports AGA.
3. Miniaturization of the hair shafts supports AGA.
4. Miniaturization of the hair shafts rules out TE.

Answer: A, C. Both AGA and TE can be present in the same individual, and often, a biopsy report will indicate androgenetic alopecia with a small component of telogen effluvium. While miniaturization supports AGA, it does not mean that TE is also not present, so it is important to do a hair pull to test for the presence of both conditions. To standardize the “hair pull,” it is important that the patient thoroughly shampoos and brushes the hair 24 hours before the visit to remove any loose (telogen) hair.

 
Question 6: What lab tests are helpful to distinguish the two conditions?

1. TSH.
2. Ferritin.
3. Dihydrotestosterone levels (DHT).
4. All the above.

Answer: A, B. Thyroid disorders and anemia can both lead to systemic stress which causes the hair to enter a resting phase in the hair growth cycle and subsequently shed 1-3 months later. The usefulness of routinely testing for testosterone and/or DHT levels in AGA is unclear and most physicians do not routinely test. Androgenetic alopecia is a disease of increased follicular sensitivity to DHT rather than one of elevated blood levels.

 
Question 7: How does a scalp biopsy differentiate TE from AGA?

1. Miniaturization will support a diagnosis of AGA.
2. Loss of follicular ostia supports AGA.
3. A peribulbar lymphocytic infiltrate would suggest TE.
4. A ratio of terminal to vellus hairs (T:V) of 3:1 or less suggests TE.

Answer: A. The hallmark presence of miniaturization is pathognomonic for androgenetic alopecia. A loss of follicular ostia would support cicatricial alopecia while a peribulbar lymphocytic infiltrate is present in alopecia areata. In telogen effluvium, one sees an increased ratio of telogen/anagen (not alterations in the T:V ratio). In AGA, the number of vellus hairs increase and terminal hair decreases, i.e., the T/V ratio lessens. Note that this data can best be determined by a horizontally cross-section biopsy rather than a vertical section, where only relatively small number of the hair follicles are examined.