Why are hormones so important?

In one of our latest articles, highly esteemed London-based consultant paediatric and adolescent endocrinologist, Dr Helen Spoudeas, explains what the hypothalamus is, gives us an insight into the importance of hormones, and outlines the four stages of brain and body growth that us humans go through. 

What are hormones?

We blame our hormones for challenging adolescent behaviours, pre-menstrual tension, fatigue, obesity, stress, and even falling in love, but, there is more to be thankful for. 

Without hormones, we would not grow, thrive, sexually mature and reproduce, or even survive. The endocrine system is primitive, highly evolved and ‘genius’. It is our body’s physiological, messaging system, vital to our wellbeing, who we become, and indeed to life itself. 

What is the hypothalamus?

The hypothalamus is a tiny gland located deep in the mid-brain close to our eyes. It is barely visible on an MRI scan. It is connected by a stalk to the pituitary gland. Together, they form the ‘Hypothalamo-Pituitary Axis’ (HPA) - a central ‘post office’ receiving and delivering the body’s ‘letters’.

The hypothalamus processes stimuli, as well as light and dark, temperature, danger, stress, hunger, thirst, and emotion, and they are responsible for sending hormones in a downstream waterfall, through the pituitary gland and onwards to each of the body’s glands (letterboxes).

These hormone ‘letters’ deserve replies, duly sent back to the HPA (human platelet antigens) in a circular, perfectly balanced system. Blood hormone levels change, adapting to different circumstances, in just the right amounts at just the right time. 

How does illness affect the HPA? 

Human platelet antigens are incredibly robust. However, any maldevelopment or harm (for example through any traumatic brain injury, infection or tumour) can have subtle or devastating consequences. 

Any chronic illness pauses the HPA developmental processes in order to allow nature to concentrate on health recovery. This is why delayed growth and puberty complicate brittle asthma and type 1 diabetes, and why anorexia nervosa and post-viral fatigue can arrest puberty or reduce stress hormone (cortisol) levels respectively, spontaneously improving on recovery.

Rare HPA developmental abnormalities, such as cysts and tumours, can be so small as to have no symptoms, while on the other hand, larger abnormalities cause growth, thyroid, as well as pubertal hormone deficiencies over time. Headaches and visual disturbance arise from increased pressure on the brain. 

Can you outline the four developmental phases of growth across the body and brain?

In the womb and during the first year of life, head growth is greater than body growth. If this early nutrition-dependent growth is compromised, head growth is maintained at the expense of lower weight and shorter height. By the same token, overfeeding will make a baby taller, but the price is lifelong obesity and a harmful pre-diabetes disposition. 

 
From two years of age onwards, our growth hormone, pulsing during sleep, controls growth along an individual trajectory (centile), determined by parental stature. Mothers worry about ensuring children are well-fed, but nutrition has little influence on growth now. Weight gain remains comparatively low until puberty.

At puberty, sex steroids and a doubling of the growth hormone increase muscle and bone mass, weight and height, secondary sexual characteristics and reproductive organs, whilst also fusing the bony growth plates. 

Completion of growth and puberty, and reproductive capacity, is marked by the onset of regular periods in girls and beard growth in boys. However, bone density and peak frontal brain growth - responsible for ‘executive’ planning functions, controlling our judgement and personality – continue to accrue under the influence of the same hormones until the age of 20 to 25.

These high-energy processes coincide with increased emotional and intellectual demands. Thus, this is a vulnerable time for fatigue, eating, gender identity and mental health disorders and an opportunity for extra rest, fresh air, mindfulness and vitamin D.     

To book an appointment with Dr Helen Spoudeas, simply head on over to her Top Doctors profile to consult with her today.