Hereditary haemochromatosis is an inherited systemic disorder of iron homeostasis characterized by progressive, excessive dietary iron absorption and pathological parenchymal deposition across multiple organ systems^{1, 2}. As the most common genetic condition in populations of Northern European ancestry—with an autosomal recessive inheritance pattern and a high carrier frequency—it represents a central diagnostic entity in clinical gastroenterology and hepatology^{1, 3}. Pathologically, impaired signalling or inadequate production of the hepatic peptide hormone hepcidin allows unrestrained intestinal iron uptake from the duodenum, leading over decades to systemic iron overload, free radical generation, and irreversible end-organ damage in the liver, pancreas, myocardium, pituitary gland, and joints^{1, 3, 4}. Early identification via biochemical screening and genetic testing is vital, as timely therapeutic intervention halts or reverses tissue injury and prevents fatal complications such as cirrhosis and hepatocellular carcinoma^{1, 3}.

Etiology & Risk Factors

• Genetic Mutations (HFE Gene): The vast majority of hereditary haemochromatosis cases are caused by mutations in the HFE gene located on chromosome 6p21.3^{1, 2}. The primary pathogenic variant is a missense mutation resulting in a cysteine-to-tyrosine substitution at amino acid 282 (C282Y homozygosity), which accounts for 80% to 90% of clinical cases in Northern European populations^{1, 2}. A secondary variant, H63D, involves a histidine-to-aspartate substitution; compound heterozygosity (C282Y/H63D) or H63D homozygosity rarely causes significant iron overload unless co-inherited with secondary hepatic cofactors^{1, 2}.
• Non-HFE (Rare) Forms of Haemochromatosis: Non-HFE forms include Type 2A (juvenile haemochromatosis caused by mutations in the hemojuvelin gene, HJV), Type 2B (hepcidin antimicrobial peptide gene, HAMP), Type 3 (transferrin receptor 2 gene, TFR2), and Type 4 (ferroportin disease caused by solute carrier family 40 member 1 gene, SLC40A1 mutations), which follow autosomal recessive or dominant inheritance and present with severe early-onset iron loading⁴.
• Demographic and Ancestral Risk Factors: Highest prevalence is observed in populations of Celtic and Northern European descent, with an estimated phenotypic frequency of approximately 1 in 300 to 1 in 500 individuals^{1, 2, 3}.
• Environmental and Acquired Cofactors: Coexisting chronic alcohol consumption, non-alcoholic fatty liver disease (NAFLD), chronic viral hepatitis (hepatitis B or C), and metabolic syndrome significantly accelerate hepatic fibrogenesis and clinical penetrance in genetically susceptible individuals.
• Sex and Physiological Status: Biological males manifest symptomatic disease earlier (typically between the 4th and 5th decades of life) due to the absence of physiological iron loss, whereas biological females are protected during their reproductive years by menstruation and pregnancy, typically presenting post-menopause (after the 5th decade)².

Pathophysiology

Normal systemic iron homeostasis is strictly regulated by hepcidin, a 25-amino acid peptide hormone synthesized predominantly by hepatocytes⁴. Hepcidin binds to ferroportin—the sole known mammalian iron exporter located on the basolateral membrane of duodenal enterocytes, macrophages, and hepatocytes—inducing its internalization and lysosomal degradation, thereby inhibiting systemic iron entry into the bloodstream⁴. In classical HFE-associated haemochromatosis, mutated HFE proteins fail to properly interact with transferrin receptor 1 (TfR1) and transferrin receptor 2 (TfR2) on the hepatocyte surface, disrupting the cellular iron-sensing apparatus⁴. Consequently, the liver erroneously perceives systemic iron deficiency, leading to inappropriately suppressed production of hepcidin despite massive total-body iron accumulation⁴.

Low circulating hepcidin levels remove the inhibitory checkpoint on ferroportin, leaving cell-surface ferroportin constitutively open and active⁴. Unrestrained duodenal enterocytes hyperabsorb dietary iron, which enters the portal circulation bound to transferrin until binding capacity is completely saturated (transferrin saturation exceeding 45% to 50%)^{1, 2, 3}. Unbound plasma iron circulates as non-transferrin-bound iron (NTBI), an extremely reactive species that readily crosses cell membranes via low-affinity divalent metal transporters into parenchymal cells of the liver, pancreas, heart, anterior pituitary, and synovium^{1, 3}. Intracellularly, excess ferrous iron undergoes Fenton chemistry, catalyzing the production of highly toxic hydroxyl radicals and reactive oxygen species (ROS)³. These free radicals induce lipid peroxidation, organelle damage, and activation of hepatic Kupffer cells and stellate cells, ultimately driving collagen deposition, multi-organ fibrosis, endocrine cell apoptosis, and eventual clinical organ failure^{1, 3}.

Clinical Presentation & Classic Clinical Signs

• History & Cardinal Symptoms:
  • Constitutional: Chronic, profound fatigue, lethargy, malaise, and asthenia are frequently the earliest and most common presenting complaints, often preceding objective organ dysfunction by years^{2, 3}.
  • Rheumatological: Arthralgias affecting the second and third metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the hands, as well as large joints (wrists, knees, hips), causing mechanical joint pain and limited mobility^{2, 3}.
  • Endocrinological & Sexual Dysfunction: Loss of libido, erectile dysfunction, secondary amenorrhea, or premature menopause resulting from iron deposition in the anterior pituitary gland leading to hypogonadotropic hypogonadism^{1, 2, 3}.
  • Cardiorespiratory: Dyspnoea on exertion, peripheral edema, palpitations, or overt symptoms of congestive heart failure secondary to iron-induced cardiomyopathy^{1, 2, 3}.
  • Metabolic: Polyuria, polydipsia, and unexplained weight loss due to iron-induced diabetes mellitus ("bronze diabetes")^{2, 3}.
• Physical Examination & Named Clinical Signs:
  • Cutaneous Pigmentation: Generalized, slate-grey or bronze hyperpigmentation (particularly prominent in sun-exposed areas, axillae, genitalia, and scars) driven by increased melanin synthesis and cutaneous iron deposition^{2, 3}.
  • Hepatomegaly: Firm, smooth hepatomegaly palpable during abdominal examination in early stages, which may progress to a nodular, shrunken liver contour if cirrhosis develops^{1, 3}.
  • Arthrography Signs: Bony swelling, tenderness, and restricted range of motion most characteristic of second and third metacarpophalangeal joint involvement (often sparing the distal interphalangeal joints, helping differentiate it from osteoarthritis).
  • Endocrine Stigmata: Loss of secondary sexual hair, testicular atrophy, and signs of chronic liver disease (spider angiomas, palmar erythema, gynaecomastia, and caput medusae if portal hypertension is established)³.

Diagnostic Workup & Interpretation (Laboratory, Imaging & ECG/Pathology)

Staging, Classification & Clinical Scoring Systems

Differential Diagnosis

Management & Treatment Protocol

• Initial Stabilization & Resuscitation:
  • Assess baseline cardiorespiratory and hepatic stability, particularly in patients presenting with decompensated heart failure or severe arrhythmias secondary to iron-induced cardiomyopathy.
  • Perform baseline staging investigations, including complete blood count, comprehensive metabolic panel, fasting blood glucose or HbA1c, thyroid function tests, morning testosterone and gonadotropin levels, electrocardiogram, and transient elastography or MRI for hepatic iron quantification and fibrosis staging¹.
• First-Line Medical / Pharmacological Therapy (with exact adult dosing):
  • Therapeutic Phlebotomy (Venesection): The cornerstone of management. Standard adult phlebotomy involves the removal of 450 to 500 mL of whole blood (approximately equivalent to 200–250 mg of elemental iron) on a weekly or biweekly schedule^{1, 3, 6}.
  • Induction Phase: Sessions are typically performed weekly in outpatient infusion centres. Pre-phlebotomy haemoglobin must be monitored prior to each session (hemoglobin should remain >11.0 g/dL or drop by no more than 2.0 g/dL from baseline; target hemoglobin threshold generally requires >12.0 g/dL). Treatment continues weekly until serum ferritin levels drop into the low-normal maintenance threshold of 50 mcg/L (range 50–100 mcg/L)¹.
  • Maintenance Phase: Once iron stores are depleted, patients require lifelong maintenance venesection, typically every 2 to 4 months (or customized based on individual iron re-accumulation rates), with ongoing monitoring of serum ferritin and transferrin saturation every 6 months to maintain ferritin between 50 and 100 mcg/L^{1, 3}.
  • Dietary Adjustments: Advise patients to avoid iron supplements, multivitamin preparations containing iron, and excessive consumption of vitamin C (which enhances non-heme iron absorption). Moderate reduction in dietary red meat is recommended, whereas complete elimination of alcohol is mandatory for patients with hepatic fibrosis or cirrhosis.
• Surgical / Interventional Indications:
  • Orthotopic Liver Transplantation: Indicated for patients who progress to end-stage liver failure (decompensated cirrhosis) or hepatocellular carcinoma refractory to locoregional therapy, though iron-depletion therapy prior to transplantation improves overall post-operative survival.
  • Cardiothoracic Interventions: Management of severe heart failure may necessitate guideline-directed medical therapy for heart failure, specialized anti-arrhythmic management, or consideration of mechanical circulatory support/cardiac transplantation in refractory iron-induced cardiomyopathy.

Complications & Prognosis

• Hepatic Complications: Progression from simple iron overload to hepatic fibrosis, micronodular cirrhosis, portal hypertension, ascites, variceal bleeding, and hepatic encephalopathy^{1, 2, 3}. Patients with established cirrhosis carry a lifelong risk of developing hepatocellular carcinoma, necessitating strict biannual ultrasound surveillance regardless of successful iron depletion^{1, 3}.
• Endocrine & Metabolic Sequelae: Permanent insulin-dependent or non-insulin-dependent diabetes mellitus ("bronze diabetes") due to iron-mediated destruction of pancreatic beta cells; hypogonadotropic hypogonadism leading to permanent infertility, erectile dysfunction, and osteoporosis; and hypothyroidism or hypoparathyroidism resulting from glandular iron deposition^{1, 2, 3}.
• Musculoskeletal Complications: Chronic, disabling arthropathy affecting the wrists and metacarpophalangeal joints, which characteristically persists and may even progress despite normalization of body iron stores due to irreversible calcium pyrophosphate dihydrate (CPPD) crystal deposition and structural cartilage damage^{2, 3}.
• Cardiovascular Complications: Restrictive or dilated cardiomyopathy presenting with refractory congestive heart failure and life-threatening ventricular arrhythmias, which represent a leading cause of mortality in untreated juvenile and severe adult-onset forms^{1, 2, 3}.
• Prognosis: When diagnosed and treated via therapeutic phlebotomy before the development of cirrhosis or diabetes, patients with hereditary haemochromatosis enjoy a normal life expectancy. Conversely, delayed diagnosis resulting in advanced cirrhosis or cardiomyopathy markedly diminishes long-term survival and elevates hepatocellular carcinoma risk^{1, 3}.