Prothrombin deficiency

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Prothrombin deficiency is a bleeding disorder that slows the blood clotting process. People with this condition often experience prolonged bleeding following an injury, surgery, or having a tooth pulled. In severe cases of prothrombin deficiency, heavy bleeding occurs after minor trauma or even in the absence of injury (spontaneous bleeding). Women with prothrombin deficiency can have prolonged and sometimes abnormally heavy menstrual bleeding. Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. Milder forms of prothrombin deficiency do not involve spontaneous bleeding, and the condition may only become apparent following surgery or a serious injury.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the F2 gene cause prothrombin deficiency. The F2 gene provides instructions for making the prothrombin protein (also called coagulation factor II), which plays a critical role in the formation of blood clots in response to injury. Prothrombin is the precursor to thrombin, a protein that initiates a series of chemical reactions to form a blood clot. After an injury, clots protect the body by sealing off damaged blood vessels and preventing further blood loss.

F2 gene mutations reduce the production of prothrombin in cells, which prevents clots from forming properly in response to injury. Problems with blood clotting can lead to excessive bleeding. Some mutations drastically reduce the activity of prothrombin and can lead to severe bleeding episodes. Other F2 gene mutations allow for a moderate amount of prothrombin activity, typically resulting in mild bleeding episodes.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Prothrombin deficiency is very rare; it is estimated to affect 1 in 2 million people in the general population.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Prolonged partial thromboplastin time · Very frequent (99-80%)

Increased time to coagulation in the partial thromboplastin time (PTT) test, a measure of the intrinsic and common coagulation pathways. Phospholipid, and activator, and calcium are mixed into an anticoagulated plasma sample, and the time is measured until a thrombus forms.

Prolonged prothrombin time · Very frequent (99-80%)

Increased time to coagulation in the prothrombin time test, which is a measure of the extrinsic pathway of coagulation. The results of the prothrombin time test are often expressed in terms of the International normalized ratio (INR), which is calculated as a ratio of the patient's prothrombin time (PT) to a control PT standardized for the potency of the thromboplastin reagent developed by the World Health Organization (WHO) using the formula: INR is equal to Patient PT divided by Control PT.

Reduced prothrombin antigen · Very frequent (99-80%)

Reduced prothrombin antigen as measured by ELISA assay. Prothrombin is a vitamin K-dependent coagulation factor that is proteolytically cleaved to form thrombin.

Abnormal bleeding · Frequent (79-30%)

An abnormal susceptibility to bleeding, often referred to as a bleeding diathesis. A bleeding diathesis may be related to vascular, platelet and coagulation defects.

Epistaxis · Frequent (79-30%)

Epistaxis, or nosebleed, refers to a hemorrhage localized in the nose.

Intracranial hemorrhage · Frequent (79-30%)

Hemorrhage occurring within the skull.

Joint hemorrhage · Frequent (79-30%)

Hemorrhage occurring within a joint.

Abnormal umbilical stump bleeding · Occasional (29-5%)

Abnormal bleeding of the umbilical stump following separation of the cord at approximately 7-10 days after birth.

Anemia · Occasional (29-5%)

A reduction in erythrocytes volume or hemoglobin concentration.

Cephalohematoma · Occasional (29-5%)

Hemorrhage between the skull and periosteum of a newborn resulting from rupture of blood vessels that cross the periosteum.

Excessive bleeding from superficial cuts · Occasional (29-5%)

An abnormally increased degree of bleeding following a superficial injury to the surface of the skin.

Intramuscular hematoma · Occasional (29-5%)

Blood clot formed within muscle tissue following leakage of blood into the tissue.

Menorrhagia · Occasional (29-5%)

Prolonged and excessive menses at regular intervals in excess of 80 mL or lasting longer than 7 days.

Microscopic hematuria · Occasional (29-5%)

Microscopic hematuria detected by dipstick or microscopic examination of the urine.

Other findings in the same source

From: Orphanet

Additional reported features include Oral cavity bleeding (Occasional (29-5%)); Post-partum hemorrhage (Occasional (29-5%)); Prolonged bleeding after dental extraction (Occasional (29-5%)); Prolonged bleeding following circumcision (Occasional (29-5%)); Prolonged bleeding following procedure (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Prothrombin deficiency is Haematology, with a haematologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which blood-cell, marrow, bleeding or clotting finding matters most?
• Does the diagnosis need confirmation or a more precise subtype?
• Which symptoms or laboratory changes should trigger earlier review?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Prothrombin deficiency. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.