Endocrinology

Endocrinology studies hormones, their production and their effects on target tissues. Feedback, transport, receptor signaling and removal connect gland activity to measured concentrations. A hormone concentration therefore cannot alone reveal every aspect of secretion or tissue responsiveness.

Luteinising hormone is a gonadotropin released by the anterior pituitary under hypothalamic control. It acts on the gonads: in testes it stimulates steroid production by Leydig cells, while in an ovarian cycle its surge helps trigger ovulation and the transition to a corpus luteum.^[ref]

The signal is dynamic. A sustained low concentration and a brief surge need not have the same physiological meaning, and a sparse sampling schedule can miss a peak. The same hormone also acts in different cellular contexts, illustrating that a hormone's identity alone does not determine one universal response. Receptor expression, developmental state and the other gonadal signals contribute to the outcome.

Hypoglycaemia is a low blood-glucose concentration under the relevant measurement conditions. Its effects depend on the level, duration and physiological context. The concentration reflects the balance of production and use rather than one unique causal process.

Thyroid-stimulating hormone is a pituitary hormone regulating thyroid activity. Its concentration is interpreted together with thyroid hormone measurements and the control pathway involved. Reduced thyroid output and impaired upstream stimulation can produce different combinations of measured values.^[ref]

Thyroid disease includes disorders of thyroid structure, secretion or both. Enlargement, inflammation and altered hormone output are different dimensions. A goitre therefore does not by itself establish hypothyroidism or excess secretion.

Hypothyroidism is insufficient thyroid-hormone action resulting from inadequate hormone availability in the usual clinical setting. Dysfunction can arise in the thyroid or in its upstream control. Measuring thyroid-stimulating hormone and thyroid hormones helps distinguish those pathways.^[ref]

Tissue swelling classically associated with severe hypothyroidism, often relatively non-pitting; distinguish it from fluid-overload anasarca.

Prolactin is a peptide hormone produced chiefly by the anterior pituitary, with an important role in milk production. Its release and physiological actions are regulated in relation to reproductive state and neural input. Milk synthesis and milk ejection are different processes and should not be attributed to one hormone interchangeably.

Hyperprolactinaemia is an elevated circulating prolactin concentration. Physiological state, altered regulation and other causes can contribute. The concentration alone does not identify a unique structural lesion of the pituitary.

The endocrine signalling system linking hypothalamic and pituitary activity with ovarian function. Suppression at one level differs from outflow obstruction.

Communication in which nervous system activity influences hormone release or neurosecretory products influence distant targets.

An endocrinologist is a physician or researcher specializing in hormones and endocrine disorders. The field relates glandular secretion and feedback to metabolic, developmental and reproductive function. Assessment of a control pathway requires more than naming one hormone.

A researcher who coauthored methods for functional assessment of isolated mitochondria, relating respiration measurements to preparation yield and integrity.^[ref]