Day: March 12, 2024

#Endocrinology

Hyperthyroidism

By Sama Mohamed

Definition & classification Hyperthyroidism is a common endocrine condition caused by an overactive thyroid gland causing an excess of thyroid hormone. Hyperthyroidism affects around 1-2% of the population. It is important to first define the terminology: Hyperthyroidism: overactive thyroid gland (i.e. increased thyroid hormone production) causing an excess of thyroid hormone and thyrotoxicosis. Thyrotoxicosis: refers to an excess of thyroid hormone, having an overactive thyroid gland is not a prerequisite (e.g. ingestion of excess thyroid hormone). Hyperthyroidism more commonly affects women than men (5-10 times more common) and may be associated with a number of autoimmune and endocrine conditions. In this note,

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#Endocrinology

Diabetes insipidus

By Sama Mohamed

Introduction Diabetes insipidus results from a deficiency of, or resistance to, anti-diuretic hormone. Anti-diuretic hormone (ADH) is a hormone synthesised in the hypothalamus and released by the posterior pituitary. Its release is triggered by a rise in plasma osmolality and its action is to cause reabsorption of water in the kidneys. The clinical consequence of an inadequate ADH response, as seen in diabetes insipidus, is an inability to concentrate urine with resulting polyuria (increased urine) and polydipsia (increased thirst). DI is a rare condition with a prevalence estimated to be 1 in 25,000. There are two major forms: Central (CDI): caused by

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#Endocrinology

Cushing’s syndrome

By Sama Mohamed

Introduction Cushing’s syndrome is caused by prolonged exposure to an excess of glucocorticoids. Clinical features depend on the duration of disease and degree of cortisol excess but include weight gain, skin changes, menstrual irregularities, glucose intolerance and mood disturbance. The cause may be endogenous or exogenous: Exogenous: i.e. derived externally – occurs due to the administration of glucocorticoids either as a medication or misuse. This is by far the most common cause. Endogenous: i.e. derived internally – occurs due to excess production of glucocorticoids by the body itself. This is very rare (estimated at 5 in 1,000,000). Cushing’s disease, which refers

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#Endocrinology

Addison’s disease

By Sama Mohamed

Introduction Addison’s disease (primary adrenal insufficiency) is caused by destruction or dysfunction of the adrenal cortex. The adrenal glands sit atop each kidney, they are an important endocrine organ responsible for the release of catecholamines (adrenaline, noradrenaline), glucocorticoids, mineralocorticoids and sex hormones. Adrenal insufficiency occurs when there is a reduction of glucocorticoid +/- mineralocorticoid production such that normal physiology is interrupted: Primary adrenal insufficiency (Addison’s disease): caused by destruction or dysfunction of the adrenal cortex. This is the focus of this note. Secondary adrenal insufficiency: caused by a reduction in adrenocorticotropic hormone release. May be seen as part of panhypopituitarism, an isolated deficiency, following brain

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#Endocrinology

Acromegaly

By Sama Mohamed

Overview Acromegaly is a condition caused by an excess of growth hormone (GH) most commonly related to a pituitary adenoma. It tends to present with macrognathia, frontal bossing and enlargement of hands and feet. Presentation may also be related to the aetiology – e.g. mass effect of a pituitary adenoma resulting in visual field defects and headache. It is associated with a number of systemic conditions (e.g. cardiovascular disease, diabetes). The condition is thought to be rare though the true prevalence is hard to establish. Recent studies estimate a prevalence of up to 1 in 1000 individuals in patients who were randomly screened.

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#Diabetes

Type 2 diabetes

By Sama Mohamed

Overview Diabetes mellitus refers to a group of metabolic disorders that result from an inability to produce and/or reduced sensitivity to insulin. Diabetes mellitus Diabetes mellitus is a chronic, multi-system disease, with profound biochemical and structural sequelae. It can be classified into four main groups: Type 1 diabetes mellitus: characterised by an inability to produce/secrete insulin due to autoimmune destruction of the beta-cells (production site of insulin) in the pancreatic islets of Langerhans. Type 2 diabetes mellitus: characterised by a combination of peripheral insulin resistance and inadequate secretion of insulin. It is strongly associated with obesity and the metabolic syndrome. Gestational diabetes

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#Diabetes

Type 1 diabetes

By Sama Mohamed

Overview Diabetes mellitus refers to a group of metabolic disorders that result from an inability to produce and/or reduced sensitivity to insulin. Classification Diabetes mellitus is a chronic, multi-system disease, with profound biochemical and structural sequelae. It can be classified into four main groups: Type 1 diabetes mellitus: characterised by an inability to produce/secrete insulin due to autoimmune destruction of the beta-cells (production site of insulin) in the pancreatic islets of Langerhan. Type 2 diabetes mellitus: characterised by a combination of peripheral insulin resistance and inadequate secretion of insulin. It is strongly associated with obesity and the metabolic syndrome. Gestational diabetes mellitus: new

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#Diabetes

Hypoglycaemia

By Sama Mohamed

Overview Hypoglycaemia refers to an abnormally low plasma glucose concentration with or without symptoms. Hypoglycaemia is very common among patients with diabetes mellitus, usually secondary to insulin or certain hypoglycaemic agents (e.g. suphonylureas). Hypoglycaemia may also occur in patients without diabetes mellitus. In this situation, hypoglycaemia is uncommon and may occur due to a range of abnormalities, some very rare. Hypoglycaemia is generally defined as an abnormally low blood glucose concentration (< 4.0 mmol/L). Normal fasting range: 4.0-5.4 mmol/L Normal post-prandial range: 4.0-7.8 mmol/L (up to two hours after eating) Clinically significant hypoglycaemia is generally defined as < 3.0 mmol/L. At this

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#Diabetes

HHS

By Sama Mohamed

Definition & classification Hyperglycaemic hyperosmolar state (HHS) is an acute diabetic emergency that occurs in patients with type 2 diabetes mellitus. HHS occurs insidiously over several days with dehydration and metabolic disturbances that are more extreme than diabetic ketoacidosis (DKA). It is characterised by: Hypovolaemia Hyperglycaemia (> 30 mmol/L) Mild or absent ketonaemia (blood ketones < 3 mmol/L) High osmolality (> 320 mOsm/kg) HHS is clinically distinct to DKA and requires a different approach to treatment. Patients are usually elderly with multiple co-morbidities, and as a result may be very unwell. The condition was previously termed Hyperglycaemic Hyperosmolar Non-ketotic Coma (HONK). The terminology was altered as

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#Diabetes

DKA

By Sama Mohamed

Introduction Diabetic ketoacidosis (DKA) is a life-threatening diabetic emergency. DKA is a severe metabolic complication of diabetes. It is typically seen in those with T1DM as a presenting feature, in patients with poor control or intercurrent illness. Hyperglycaemia results in osmotic diuresis and electrolyte abnormalities, which requires prompt recognition and management. The condition is characterised by a biochemical triad of hyperglycaemia, ketonaemia and acidosis. Hyperglycaemia: > 11.0 mmol/L or known DM Ketonaemia: ≥ 3 mmol/L or significant ketonuria (> 2+ on dipstick) Acidosis: bicarbonate < 15.0 mmol/L and/or venous pH < 7.3 Epidemiology DKA represents an acute hyperglycaemic complication of diabetes that

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