Telogen effluvium (TE) and androgenetic alopecia (AGA) are common, especially among women. There are many ways to differentiate a shedding disorder (TE) from AGA - and some women have both.
A clinical examination of the scalp, a biopsy and a so called "hair collection" are three methods to evaluate a patient's diagnosis. Exactly which one I use depends on the specific clinical situation. Certainly not everyone with hair loss needs a biopsy and not everyone needs to perform a hair collection.
There are many different ways to perform a hair collection. Rebora studied the use of the 5 day hair collection, where shampooed hairs are trapped on a gauze 5 days after shampooing. The collected hairs are divided into three groups: telogen vellus hairs (less than 3 cm), intermediate hairs (3-5 cm) and long hairs (more than 5 cm). The presence of more than 10 % non broken hairs 3 cm or less is suggestive of the diagnosis of androgenetic alopecia (AGA).
Reference
Distinguishing androgenetic alopecia from chronic telogen effluvium when associated in the same patient: a simple noninvasive method. Rebora A, et al. Arch Dermatol. 2005.
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
It is often said that miniaturization of hairs (progressive thinning of hairs) is a main feature specific to men and women with androgenetic alopecia. This is not entirely accurate.
Miniaturization can be seen in many conditions including traction alopecia (shown here), alopecia areata as well as androgenetic alopecia.
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
It is often said that the "miniaturization" of hairs (ie the progressive thinning of hairs) is a key feature specific to men and women with androgenetic alopecia. However, this is not accurate.
Miniaturization can be seen in many conditions including traction alopecia, alopecia areata (shown here) as well as androgenetic alopecia.
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
In the early stages of androgenetic alopecia (first few years), miniaturized hairs grow almost the same length as original hairs (not quite but close).
As time passes, and if androgenetic alopecia progresses, them miniaturized hairs grow in the scalp for shorter and shorter periods. In advanced cases, hairs affected by androgenetic alopecia grow for only a 2-3 months - and are very, very short and very, very thin. We call these "vellus-like" hairs rather than miniaturized hairs but they are a type of miniaturized hair. Over time, vellus like hairs just don't grow any more.
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
Minoxidil is FDA approved for treating male and female androgenetic alopecia. It has been studied in humans for over 35 years. However, it is not well known among users of minoxidil that minoxidil may have a unique toxicity to cats. That is not to say that cat owners can not use minoxidil - but important lessons come from a 2004 study in the veterinary literature.
DeClementini and colleagues reported 2 cats who died after their owners applied minoxidil to areas of hair loss on the cat. The first cat was a 3 year old cat had just one drop applied to an area of hair loss . That cat had trouble breathing, high heart rate, water in the lungs (pulmonary edema and pleural effusion) and showed increased liver enzymes. The cat died 15 hours later.
The second cat was a 7 year old cat and the owners applied an unknown amount of 5 % minoxidil solution to an area of hair loss and left the home for three days. Upon returning to the home, the owners found the cat also having difficulty breathing. Veterinarians confirmed pulmonary edema and pleural effusions. That cat died 10 hours later despite supportive care.
These are important lessons. Minoxidil must not be applied to cats and cats should not have the opportunity to play with the hair of owners who have applied minoxidil for their own hair loss. Most of what is needed though is just common sense. It is possibly to have a cat and have minoxidil users in the home.
Minoxidil may be uniquely toxic to cats and less toxic to other pets like dogs. A 1997 study involved the application of 3 % minoxidil to hairless puppies (descendants of Mexican hairless dogs) for 31 days. Side effects were not observed. However, minoxidil should never be applied to any animal.
Reference
Suspected toxicosis after topical administration of minoxidil in 2 cats. Journal of Veterinary Emergency and Critical Care 2004; 14:287-292
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
Minoxidil can raise heart rate in some individuals
One uncommon side effect from minoxidil is an increase in heart rate. This is not the only thing that minoxidil is doing in this situation. It's actually primary lowering blood pressure and in turn the body increases heart rate to compensate.
I'm often asked if one needs to stop. This needs to be handled on a case by case basis. Some people will say to me " my heart rate goes up when I exercise ... so what's the difference?"
During exercise both heart rate and blood pressure go up. It's a very different physiology than minoxidil. A person's heart rate also goes up (and blood pressure goes down) when hey are dehydrated and we know this is not good. A person's heart rate can go up (and blood pressure go down) with topical minoxidil. Fortunately, this does not happen to everyone. But if there are significant heart rate changes with minoxidil, I advise checking with one's physician about whether or not to stop. This is especially important for those over 65.
This article was written by Dr. Jeff Donovan, a Canadian and US board certified dermatologist specializing exclusively in hair loss.
