Glossary

Browse through glands, hormones and endocrine conditions.
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ovarian hyperstimulation syndrome

a condition caused by raised gonadotrophin levels, leading to enlargement of the ovaries and pain in the abdomen. Can occur during IVF treatment when ovaries are stimulated to release eggs for harvesting.

ovarian reserve

the number of eggs a woman has left in her ovaries. A woman is born with all her eggs, which gradually reduce in number with age.

ophthalmology

the study of eyes and conditions that affect the eyes.

osteonecrosis

death (or breaking down) of bone tissue.

Osteoporosis

Osteoporosis is a bone disorder caused by loss of bone mass, resulting in abnormal bone structure and an increased risk of fracture.

optic nerve

the nerve behind the eye.

Oestradiol

Oestradiol is a powerful reproductive hormone that has a wide range of actions in both men and women.

octreotide

a substance similar to the hormone somatostatin, which is used in nuclear medicine scans to detect a neuroendocrine tumour.

oncologist

a doctor that specialises in the treatment of cancer.

oestrogen

a type of sex steroid hormone found in men and women responsible for secondary sexual characteristics. There are three oestrogens – oestrone, oestradiol and oestriol – the most potent of which is oestradiol.

ovulation

the process by which an egg is released from the ovary at the mid-point of the menstrual cycle (around day 14). It is triggered by a surge in luteinising hormone from the pituitary gland; this hormone is measured in ovulation kits.

Oestriol

Oestriol is a hormone made during pregnancy that can be used to measure fetal health and predict when birth may happen.

Oestrone

Oestrone is a hormone produced by the ovaries. It is one of the major oestrogens in postmenopausal women.

Oxytocin

Oxytocin is a hormone that acts on organs in the body (including the breast and uterus) and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, and aspects of human behaviour.

Ovaries

The ovaries produce and release eggs (oocytes) into the female reproductive tract at the mid-point of each menstrual cycle. They also produce the female hormones oestrogen and progesterone.

Obesity

Obesity is an excess of calories stored in the form of fat. It is an increasing public health and medical problem associated with reduced quality and length of life.

obese

the word used to describe a person whose body mass index (BMI = weight/ height2, where weight is in kilograms and height is in metres) is greater than 30.


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