Hair loss may be caused by hormonal alterations, thyroid disorders, certain medications, rapid weight loss, and nutrient deficiencies [1].
Understanding these triggers is critical because hair shedding often serves as an early warning sign for systemic health issues. When the body lacks essential minerals or faces endocrine instability, it may prioritize vital organs over hair follicles, leading to visible thinning.
Medical professionals in Brazil said that thyroid dysfunction, including both hyperthyroidism and hypothyroidism, can disrupt the hair growth cycle [1, 5]. These conditions alter hormone levels that regulate the follicles, which can result in increased shedding [4, 5].
Nutritional gaps also play a significant role in follicle health. Specifically, a deficiency in ferritin or iron can interrupt the growth cycle of the follicle [3]. In some cases, a lack of iron appears as a primary cause of hair loss before a patient develops clinical anemia [4].
Other triggers include the use of specific medications, such as lithium, and the physiological stress caused by rapid weight loss [1]. These factors deprive the follicles of the necessary nutrients or chemical balance required to maintain the hair shaft.
While some hair loss occurs without a known cause, characterized by localized, rounded patches, most shedding is linked to these identifiable biological shifts [2]. To provide a baseline for what is typical, experts said that normal daily hair loss is considered 50 to 100 strands [2].
When shedding exceeds this range, it may indicate an underlying medical condition rather than simple genetics or stress [3, 4].
“Normal daily hair loss is considered 50 to 100 strands.”
This information shifts the perspective on hair loss from a purely cosmetic or genetic concern to a potential diagnostic marker. By identifying shedding as a symptom of ferritin deficiency or thyroid dysfunction, clinicians can use dermatological changes to screen for broader metabolic and endocrine imbalances.
