Phenytoin: Mechanism of Action and Adverse Effects

Phenytoin is a medication used to manage seizures. Its mechanism of action involves binding to sodium channels, which increases their refractory period. However, the drug is associated with a large number of adverse effects, which can be categorized as acute, chronic, idiosyncratic, and teratogenic. Acute effects include dizziness, diplopia, nystagmus, slurred speech, ataxia, confusion, and seizures. Chronic effects include gingival hyperplasia, hirsutism, coarsening of facial features, drowsiness, megaloblastic anemia, peripheral neuropathy, enhanced vitamin D metabolism causing osteomalacia, lymphadenopathy, and dyskinesia. Idiosyncratic effects include fever, rashes, hepatitis, Dupuytren’s contracture, aplastic anemia, and drug-induced lupus. Teratogenic effects are associated with cleft palate and congenital heart disease. Although routine monitoring of phenytoin levels is not necessary, trough levels should be checked before dosing in cases of dose adjustment, suspected toxicity, or non-adherence to the prescribed medication.

Lynch syndrome is a genetic condition that increases the risk of developing colorectal cancer by over 80%. It also raises the risk of other cancers such as endometrial, stomach, breast, ovarian, small bowel, pancreatic, prostate, urinary tract, kidney, and liver cancer. Genetic testing is recommended for anyone diagnosed with colorectal cancer, regardless of age.

Breast cancer (BRCA) mutations are inherited in an autosomal dominant pattern and significantly increase the risk of developing breast, ovarian, prostate, and pancreatic cancer. These cancers tend to occur at a younger age than in the general population. While there is a possible link to colorectal pathology, other genetic syndromes should be considered first when looking for a genetic cause of cancer.

Cowden syndrome is a rare genetic condition characterized by benign growths called hamartomas on various parts of the body. It increases the risk of developing breast, thyroid, or endometrial cancer but has no association with colorectal cancer.

Familial adenomatous polyposis is an autosomal dominant condition that causes widespread colorectal adenomas, with polyps usually developing in late childhood. This greatly increases the risk of colorectal cancer, and prophylactic colectomy is often performed. Screening is recommended for those with an affected first-degree relative or multiple polyps detected on colonoscopy.

Von Hippel-Landau (VHL) syndrome is an autosomal dominant condition that causes multiple benign tumors and cysts in various parts of the body, including the brain, spinal cord, eyes, adrenals, kidneys, and pancreas. It increases the risk of renal and pancreatic cancer but has no association with colorectal cancer.

Managing High INR Levels in Patients on Warfarin: Treatment Options

When a patient on warfarin presents with a high INR level, it is important to take immediate action to prevent spontaneous bleeding and haemorrhage. Here are some treatment options and their implications:

1. Give a dose of vitamin K immediately and re-check her INR in 24 hours: Administering vitamin K is necessary to reverse the effects of warfarin, which is a vitamin K antagonist. In this situation, it is important to act quickly to reduce the INR level and prevent haemorrhage.

2. Give intramuscular (IM) vitamin K immediately and re-check her INR in 24 hours: While IM vitamin K can be given in cases where peripheral access is difficult, it is slower acting. In a situation with a high INR level, it is important to reduce the INR as soon as possible to prevent haemorrhage.

3. Give vitamin K immediately and re-check her INR in one week: While giving vitamin K is necessary to prevent spontaneous haemorrhage, it is important to recheck the INR relatively soon to ensure it has dropped below the required range. Waiting a week would be too long, and the INR should be rechecked within 24 hours of administering vitamin K.

4. Stop warfarin for life: If the patient has no actual side-effects from warfarin, such as anaphylaxis, they can continue to use it long-term with tighter control.

5. Switch from warfarin to aspirin: Aspirin cannot be used as a substitute for warfarin as it does not prevent thrombosis.

In conclusion, managing high INR levels in patients on warfarin requires prompt action to prevent haemorrhage. Vitamin K administration is necessary, and the INR level should be rechecked within 24 hours to ensure it has dropped below the required range.

Sickle cell patients may experience thrombotic crises due to factors such as infection, dehydration, or deoxygenation. In this case, the patient’s severe pain and recent infection suggest a thrombotic crisis. Other types of crises, such as sequestration crises that present with acute chest syndrome, aplastic crises caused by parvovirus infection, or haemolytic crises with increased haemolysis, may have different symptoms. A thyrotoxic crisis would not be related to sickle cell disease.

Sickle cell anaemia is a condition that involves periods of good health with intermittent crises. There are several types of crises that can occur, including thrombotic or painful crises, sequestration, acute chest syndrome, aplastic, and haemolytic. Thrombotic crises, also known as painful crises or vaso-occlusive crises, are triggered by factors such as infection, dehydration, and deoxygenation. These crises are diagnosed clinically and can result in infarcts in various organs, including the bones, lungs, spleen, and brain.

Sequestration crises occur when sickling occurs within organs such as the spleen or lungs, leading to pooling of blood and worsening of anaemia. This type of crisis is associated with an increased reticulocyte count. Acute chest syndrome is caused by vaso-occlusion within the pulmonary microvasculature, resulting in infarction in the lung parenchyma. Symptoms include dyspnoea, chest pain, pulmonary infiltrates on chest x-ray, and low pO2. Management involves pain relief, respiratory support, antibiotics, and transfusion.

Aplastic crises are caused by infection with parvovirus and result in a sudden fall in haemoglobin. Bone marrow suppression leads to a reduced reticulocyte count. Haemolytic crises are rare and involve a fall in haemoglobin due to an increased rate of haemolysis. It is important to recognise and manage these crises promptly, as they can lead to serious complications and even death.

After undergoing surgery, a woman presents with leg pain. Several potential causes are considered, including deep-vein thrombosis (DVT), acute limb ischaemia, air embolus, lumbar disc herniation, and paradoxical embolus. Based on the patient’s risk factors and symptoms, DVT is deemed the most likely diagnosis. Other causes are ruled out due to lack of relevant history or low probability. Understanding the possible causes of leg pain after urological surgery can help healthcare providers make an accurate diagnosis and provide timely treatment.

The use of Tamoxifen is limited to pre-menopausal women, and there is a continuing discussion regarding the duration of therapy, whether it should be for 5 years or more.

Breast cancer management varies depending on the stage of the cancer, type of tumor, and patient’s medical history. Treatment options may include surgery, radiotherapy, hormone therapy, biological therapy, and chemotherapy. Surgery is typically the first option for most patients, except for elderly patients with metastatic disease who may benefit more from hormonal therapy. Prior to surgery, an axillary ultrasound is recommended for patients without palpable axillary lymphadenopathy, while those with clinically palpable lymphadenopathy require axillary node clearance. The type of surgery offered depends on various factors, such as tumor size, location, and type. Breast reconstruction is also an option for patients who have undergone a mastectomy.

Radiotherapy is recommended after a wide-local excision to reduce the risk of recurrence, while mastectomy patients may receive radiotherapy for T3-T4 tumors or those with four or more positive axillary nodes. Hormonal therapy is offered if tumors are positive for hormone receptors, with tamoxifen being used in pre- and peri-menopausal women and aromatase inhibitors like anastrozole in post-menopausal women. Tamoxifen may increase the risk of endometrial cancer, venous thromboembolism, and menopausal symptoms. Biological therapy, such as trastuzumab, is used for HER2-positive tumors but cannot be used in patients with a history of heart disorders. Chemotherapy may be used before or after surgery, depending on the stage of the tumor and the presence of axillary node disease. FEC-D is commonly used in the latter case.

For provoked cases of venous thromboembolism, such as those following recent surgery, warfarin treatment is typically recommended for a duration of three months. However, for unprovoked cases, where the cause is unknown, a longer duration of six months is typically recommended.

NICE updated their guidelines on the investigation and management of venous thromboembolism (VTE) in 2020. The use of direct oral anticoagulants (DOACs) is recommended as first-line treatment for most people with VTE, including as interim anticoagulants before a definite diagnosis is made. Routine cancer screening is no longer recommended following a VTE diagnosis. The cornerstone of VTE management is anticoagulant therapy, with DOACs being the preferred choice. All patients should have anticoagulation for at least 3 months, with the length of anticoagulation being determined by whether the VTE was provoked or unprovoked.

Tumor Markers and Serum Electrophoresis: Their Role in Diagnosing Multiple Myeloma

Multiple myeloma is a malignant disease of plasma cells that can cause renal failure, normocytic anemia, hypercalcemia, and raised ESR. To diagnose multiple myeloma, serum electrophoresis, serum-free light-chain assay, and assessment of urinary Bence Jones protein are recommended. Serum electrophoresis confirms the presence of a paraprotein, which may be due to myeloma or MGUS. Further tests, such as bone marrow biopsy, magnetic resonance imaging, and immunofixation of serum and urine, are usually carried out in secondary care to confirm the diagnosis.

Carcinoembryonic antigen (CEA), CA 19-9, serum lactate dehydrogenase (LDH), and CA125 are tumor markers used to monitor disease progression in various cancers. However, there is no role for these markers in diagnosing multiple myeloma. CEA is mainly used to monitor the progress of treatment for colonic cancer, while CA 19-9 is used to monitor disease progression in pancreatic cancer. LDH is raised in lymphoma and certain types of testicular cancer, and CA125 is used in the diagnosis of ovarian cancer. Therefore, these markers are not useful in diagnosing multiple myeloma.

MGUS is a possible differential diagnosis for elevated paraproteins in the blood.

Thrombocytopenia is a characteristic feature of haemolytic uraemic syndrome.

The presence of paraproteins in the blood is an abnormal finding and not a normal variant.

While a viral infection may cause neutropenia, it would not typically result in the presence of paraproteins in the blood.

Paraproteinaemia is a medical condition characterized by the presence of abnormal proteins in the blood. There are various causes of paraproteinaemia, including myeloma, monoclonal gammopathy of uncertain significance (MGUS), benign monoclonal gammopathy, Waldenstrom’s macroglobulinaemia, amyloidosis, CLL, lymphoma, heavy chain disease, and POEMS. Benign monoclonal gammopathy can also cause paraproteinaemia, as well as non-lymphoid malignancy (such as colon or breast cancer), infections (such as CMV or hepatitis), and autoimmune disorders (such as RA or SLE).

Paraproteinaemia is a medical condition that is characterized by the presence of abnormal proteins in the blood. This condition can be caused by various factors, including myeloma, MGUS, benign monoclonal gammopathy, Waldenstrom’s macroglobulinaemia, amyloidosis, CLL, lymphoma, heavy chain disease, and POEMS. Additionally, benign monoclonal gammopathy, non-lymphoid malignancy (such as colon or breast cancer), infections (such as CMV or hepatitis), and autoimmune disorders (such as RA or SLE) can also cause paraproteinaemia. It is important to identify the underlying cause of paraproteinaemia in order to determine the appropriate treatment plan.

Treatment Options for Acute Leukaemia

Acute leukaemia, specifically acute myeloid leukaemia (AML), is characterized by an increase in undifferentiated blast cells in the bone marrow and blood, leading to marrow failure. The traditional treatment approach for AML involves three components: induction, consolidation, and maintenance chemotherapy. Combination chemotherapy is used to eradicate blast cells, with maintenance chemotherapy given to eliminate any remaining disease.

Iron transfusions may be necessary to treat anaemia or platelet deficiency, but they are not a direct treatment for acute leukaemia. Patients with leukaemia are at risk of graft-versus-host disease, so they are given irradiated blood components.

Intravenous immunoglobulins are not a treatment for acute leukaemia but may be used to prevent infection in patients with hypogammaglobulinaemia resulting from cancer treatment.

Radiotherapy is not a first-line treatment for acute leukaemia, but it may be used to treat disease that has spread to the brain or spinal cord. Total body radiotherapy can also be used before a stem-cell transplant to reduce the risk of transplant rejection.

Stem-cell transplants can be allogeneic (from a matched or partially matched donor) or autologous (from the patient’s own stem cells) and are used after remission induction with chemotherapy. The goal is to restore the body’s ability to produce normal blood cells and can be curative, but it is not a first-line treatment.

Understanding Treatment Options for Acute Leukaemia