Diaphoresis

Also written as Hyperhidrosis (pathologic), Profuse sweating.

Diaphoresis is excessive sweating beyond thermoregulatory needs, often signaling systemic illness. Recognising patterns helps uncover underlying cardiac, endocrine, infectious, or drug‑related causes.

Overview

Sweating is a normal autonomic response to heat, stress, or fever. Diaphoresis denotes abnormal, often sudden, sweating that may be focal or generalized and signals a physiologic disturbance.

• Distinguish primary hyperhidrosis (idiopathic) from secondary diaphoresis (systemic disease).
• Note timing (night sweats vs. exertional), distribution, and associated symptoms.

Key concepts

The sympathetic cholinergic pathway drives eccrine glands; disruption by cytokines, catecholamines, or toxins produces diaphoresis. Recognise the three clinical patterns:

• Fever‑related diaphoresis (infection, sepsis, malaria).
• Neuro‑cardiac diaphoresis (MI, arrhythmia, pheochromocytoma).
• Drug‑induced diaphoresis (withdrawal, anticholinergics, opioids).

Clinical relevance

Excessive sweating can be the first clue to life‑threatening conditions. A systematic approach—history, exam, focused investigations—prioritises urgent diagnoses.

• Complete blood count: Is there leukocytosis or anaemia suggesting infection or haemolysis? → Elevated WBC supports bacterial sepsis; low Hb may point to malaria or haemolytic crisis.
• Serum lactate: Is tissue hypoperfusion present? → High lactate indicates shock, prompting aggressive resuscitation.
• ECG: Is there myocardial ischaemia? → ST changes or new arrhythmia confirm cardiac cause; if unavailable, assess chest pain, vitals, and give aspirin if MI suspected.
• Blood cultures: Is bacteremia present? → Positive cultures guide antibiotics; if unavailable, start empiric broad‑spectrum therapy in septic patients.
• Urine dipstick for ketones: Is diabetic ketoacidosis a possibility? → Ketones + hyperglycaemia confirm DKA; treat with insulin and fluids.

• Identify red‑flag features: fever >38 °C, chest pain, dyspnoea, altered mental status.
• Consider tropical infections (malaria, TB, HIV) in endemic settings.

Exam pearls

Examiners test your ability to link diaphoresis to underlying pathology and to act swiftly.

• When diaphoresis accompanies fever and rigors, think malaria in endemic areas before ordering a rapid test.
• In a patient with chest pain and diaphoresis, prioritize ECG and aspirin over exhaustive labs.

Common mistakes

Students often label any sweating as primary hyperhidrosis or overlook systemic causes.

• Failing to ask about night sweats, which point to TB or lymphoma.
• Missing drug withdrawal (e.g., opioids, alcohol) as a reversible cause.

Questions an examiner may ask

• A 45‑year‑old with crushing chest pain and cold, clammy skin – what is your immediate management? — Obtain ECG, give aspirin, oxygen, and prepare for reperfusion; diaphoresis signals sympathetic surge in MI.
• A traveller returns from sub‑Saharan Africa with fever, chills, and night sweats – which test should you order first? — Rapid malaria antigen test; early detection prevents severe parasitaemia.
• A patient on chronic opioids presents with tremor, anxiety, and diaphoresis after missing doses – what is the underlying mechanism? — Opioid withdrawal causing autonomic hyperactivity; treat with tapering or buprenorphine.
• During a routine exam you note focal hand sweating without systemic signs – what diagnosis should you consider? — Primary focal hyperhidrosis; reassure and discuss topical antiperspirants.
• A diabetic patient arrives with abdominal pain, vomiting, and profuse sweating – what lab is essential and why? — Serum ketones and glucose; positive ketones indicate DKA requiring insulin and fluids.
• A patient with known pheochromocytoma reports episodic headaches, palpitations, and sweating – which investigation confirms the diagnosis? — Plasma free metanephrines; elevated levels confirm catecholamine excess.
• In a low‑resource clinic you suspect sepsis but lack lactate measurement – what clinical signs guide your decision to start fluids and antibiotics? — Hypotension, tachycardia, altered mental status, and warm extremities indicate distributive shock.
• A postoperative patient develops sudden diaphoresis, tachypnoea, and chest discomfort – what complication must you rule out? — Pulmonary embolism; obtain CT pulmonary angiography or bedside ultrasound if imaging unavailable.

When to seek help

• Sudden onset chest pain with diaphoresis – possible myocardial infarction.
• High fever with rigors and profuse sweating – sepsis or malaria.
• Altered mental status plus diaphoresis – toxic ingestion or adrenal crisis.

Quick questions

Is diaphoresis always a sign of fever?

No; it can occur with pain, anxiety, cardiac ischaemia, endocrine tumours, or drug effects.

How does malaria cause night sweats?

Cyclical parasite replication triggers cytokine release and fever spikes, followed by profuse sweating as temperature falls.

When is primary hyperhidrosis diagnosed?

When excessive sweating is focal, chronic, begins before age 25, and no systemic disease is identified.