6.11 Hematologic, Immunologic, and Oncology Supportive Care
Key Takeaways
- Iron deficiency anemia is confirmed by a low ferritin; oral iron is best absorbed as a single daily or alternate-day dose taken on an empty stomach with a source of vitamin C.
- Vitamin B12 deficiency must be corrected before or alongside folate, because folate alone corrects the anemia while allowing irreversible neurological damage to progress.
- Anaphylaxis is treated with intramuscular epinephrine into the anterolateral thigh; antihistamines and corticosteroids are adjuncts that never replace it.
- Live vaccines are contraindicated in significantly immunosuppressed patients, including solid organ transplant recipients on maintenance immunosuppression.
- Febrile neutropenia — a single temperature of 38.3 degrees Celsius or 38.0 sustained for an hour with an absolute neutrophil count below 0.5 x 10^9/L — is a medical emergency requiring antibiotics within one hour.
6.11 Hematologic, Immunologic, and Oncology Supportive Care
Exam Focus: These topics appear in the Pharmacotherapeutics subcategory and in Appendix 1 of the PEBC syllabus. High-yield items involve interpreting a complete blood count, recognising an oncologic or immunologic emergency, and counselling an immunosuppressed patient.
The Anemias
Classify first by mean corpuscular volume (MCV), then confirm with iron studies and vitamin levels.
| Type | MCV | Confirmatory findings | Treatment |
|---|---|---|---|
| Iron deficiency | Low (microcytic) | Ferritin low, transferrin saturation low, total iron-binding capacity high | Oral iron; investigate the source of blood loss |
| Anemia of chronic disease | Normal or low | Ferritin normal or high, transferrin saturation low | Treat the underlying disease |
| Vitamin B12 deficiency | High (macrocytic) | Low B12, raised methylmalonic acid and homocysteine | Cyanocobalamin oral high dose or intramuscular |
| Folate deficiency | High (macrocytic) | Low red cell folate, raised homocysteine, normal methylmalonic acid | Folic acid, after excluding B12 deficiency |
Iron therapy counselling. Elemental iron content differs sharply between salts — ferrous fumarate 300 mg contains about 100 mg elemental iron, ferrous sulfate 300 mg about 60 mg, and ferrous gluconate 300 mg about 35 mg. Current evidence supports a single daily dose or alternate-day dosing, because more frequent dosing raises hepcidin and reduces fractional absorption. Take on an empty stomach with a vitamin C source; separate from calcium, antacids, proton pump inhibitors, tetracyclines, quinolones, and levothyroxine by at least two hours. Warn about black stools (expected) and constipation, and continue therapy for three months after hemoglobin normalises to refill stores.
Vitamin B12 before folate. Both correct the megaloblastic anemia, but only B12 replacement halts subacute combined degeneration of the spinal cord. Giving folate alone to a B12-deficient patient masks the hematologic sign while the neurological injury becomes permanent. Long-term metformin and proton pump inhibitor use are common contributors to B12 deficiency.
Drug-induced hematologic disorders to recognise: clozapine and carbamazepine (agranulocytosis), linezolid and valproate (thrombocytopenia), heparin (heparin-induced thrombocytopenia, a prothrombotic state despite the falling platelet count), methotrexate and trimethoprim (megaloblastic change), and dapsone, primaquine, nitrofurantoin, and sulfonamides (hemolysis in glucose-6-phosphate dehydrogenase deficiency).
Hypersensitivity and Anaphylaxis
Distinguish a true immunoglobulin E-mediated allergy from an intolerance. Rash alone years earlier is not the same as urticaria with angioedema and bronchospasm, and mislabelled penicillin allergy drives the use of broader, more toxic, and less effective antibiotics.
Anaphylaxis management is a fixed sequence:
- Intramuscular epinephrine into the anterolateral thigh, 0.01 mg/kg to a maximum of 0.5 mg, repeated every 5 to 15 minutes as needed. There is no absolute contraindication.
- Call emergency services; position the patient supine with legs elevated unless breathing is compromised.
- Adjuncts only after epinephrine: antihistamines for cutaneous symptoms, inhaled beta-2 agonist for bronchospasm, corticosteroids historically used for biphasic reactions.
Counsel every auto-injector user to carry two devices, demonstrate the technique with a trainer, check expiry dates, and seek emergency care after any use because of biphasic reactions. Patients on beta-blockers may respond poorly to epinephrine and can require glucagon.
Desensitisation allows a needed drug to be given despite immunoglobulin E-mediated allergy, is performed under specialist supervision, and confers only temporary tolerance that is lost once therapy is interrupted.
Transplant Immunosuppression and Autoimmune Disease
Solid organ transplant maintenance usually combines a calcineurin inhibitor (tacrolimus or cyclosporine), an antimetabolite (mycophenolate or azathioprine), and a corticosteroid.
- Tacrolimus and cyclosporine are narrow-therapeutic-index CYP3A4 substrates. Grapefruit juice, azole antifungals, macrolides, and diltiazem raise levels; rifampin, phenytoin, carbamazepine, and St. John's wort lower them and can cause graft rejection.
- Adverse effects include nephrotoxicity, tremor, hypertension, hyperkalemia, and new-onset diabetes; cyclosporine additionally causes gingival hyperplasia and hirsutism.
- Prophylaxis typically includes trimethoprim-sulfamethoxazole for Pneumocystis jirovecii and valganciclovir for cytomegalovirus in at-risk recipients.
- Live vaccines are contraindicated after transplantation. Inactivated vaccines, including annual influenza, are recommended, ideally completed before transplantation.
Systemic lupus erythematosus is managed with hydroxychloroquine as background therapy for nearly all patients, with corticosteroids, immunosuppressants, and belimumab layered by organ involvement. Sun protection is a therapeutic measure. Drug-induced lupus, classically from hydralazine, procainamide, isoniazid, or minocycline, spares the kidneys and central nervous system and resolves after the drug is stopped.
Oncology Supportive Care
Pharmacists rarely select cytotoxic regimens on this examination, but they are expected to manage the consequences.
| Complication | Recognition | Management |
|---|---|---|
| Febrile neutropenia | One temperature of 38.3 degrees Celsius, or 38.0 sustained one hour, with absolute neutrophil count below 0.5 x 10^9/L | Emergency: broad-spectrum antibiotics within one hour |
| Chemotherapy-induced nausea and vomiting | Acute, delayed, anticipatory, breakthrough | Prophylaxis matched to emetogenic risk: 5-HT3 antagonist, neurokinin-1 antagonist, dexamethasone, olanzapine |
| Mucositis | Painful oral ulceration | Bland rinses, good oral care, analgesia; avoid alcohol-containing mouthwash |
| Tumour lysis syndrome | High potassium, phosphate, and urate; low calcium; acute kidney injury | Hydration, allopurinol or rasburicase |
| Cancer pain | Persistent, often mixed | Scheduled long-acting opioid with breakthrough dosing, plus adjuvants; constipation prophylaxis from day one |
Never treat a fever in a neutropenic patient as a minor ailment. Counsel patients on cytotoxic therapy to report fever, bleeding, or new bruising immediately, to handle oral cytotoxic tablets without crushing or splitting, and to follow safe handling of body fluids for the period specified for their regimen.
A patient with macrocytic anemia has a low serum vitamin B12, a low red cell folate, and paresthesias in both feet. Which sequence of replacement is correct?
A patient develops urticaria, throat tightness, and wheeze minutes after a peanut exposure. Which is the correct first intervention?
A kidney transplant recipient on tacrolimus is prescribed clarithromycin for a respiratory infection. What is the principal concern?
A patient on chemotherapy phones with a temperature of 38.5 degrees Celsius. His last complete blood count showed an absolute neutrophil count of 0.3 x 10^9/L. What should the pharmacist advise?