Hormonal disorders
Too little or too much of a hormone causes disorders: dwarfism and gigantism (growth hormone), goitre and cretinism (thyroid), and diabetes mellitus (insulin).
Disorders of growth hormone and thyroxine
| Hormone | Problem | Disorder | Signs |
|---|---|---|---|
| Growth hormone | Too little in childhood | Dwarfism | Very short height; body proportions and intelligence are normal |
| Growth hormone | Too much in childhood | Gigantism | Very tall, with very long bones |
| Growth hormone | Too much in adults | Acromegaly | Large hands, feet, jaw and face bones |
| Thyroxine | Too little iodine in food | Simple goitre | Swollen thyroid in the neck |
| Thyroxine | Too little in children | Cretinism | Stunted growth, slow mental development, puffy face |
| Thyroxine | Too little in adults | Myxoedema | Low BMR, puffy face and skin, tiredness, feeling cold |
| Thyroxine | Too much | Exophthalmic goitre (Graves' disease) | Bulging eyes, high BMR, fast heartbeat, weight loss, nervousness |
Other hormonal disorders
| Hormone | Problem | Disorder | Signs |
|---|---|---|---|
| Parathormone | Too little | Tetany | Low blood calcium; painful muscle spasms |
| Insulin | Too little | Diabetes mellitus | High blood sugar, sugar in urine, passing urine often, great thirst and hunger |
| Vasopressin (ADH) | Too little | Diabetes insipidus | Large amounts of watery urine with no sugar; great thirst |
Diabetes mellitus vs diabetes insipidus
Both cause frequent urination and thirst, but only diabetes mellitus puts sugar in the urine.
Simple goitre vs exophthalmic goitre
Use iodised salt in cooking to prevent goitre and cretinism; iodine shortage is most common in hilly and flood-prone areas where the soil has little iodine. A balanced diet with millets, vegetables and less sugar, plus daily exercise, lowers the risk of diabetes in later life.
2 marks: “What is cretinism? What causes it?” Stunted growth and slow mental development in children, caused by too little thyroxine.
2 marks: “Distinguish between dwarfism and gigantism.” Dwarfism: too little growth hormone in childhood, very short. Gigantism: too much growth hormone in childhood, very tall.
4 marks: “What is diabetes mellitus? Write its cause and symptoms.” A disorder due to lack of insulin; high blood sugar, sugar in urine, frequent urination, thirst and hunger; controlled by diet, exercise and insulin.
Low thyroxine: Cretinism in Children (both C), Myxoedema in Mature adults (both M). Too little GH makes a Dwarf, too much makes a Giant.