Hematology: The carrier and the clot.

The kidney is the oxygen sensor. Cells in the cortex read how much oxygen is arriving, and when it falls they release erythropoietin. The marrow answers.

An erythroblast takes about seven days to become a red cell. The marrow ships roughly 200 billion of them a day. Each one then works for about 120 days with no nucleus and no mitochondria, which means it cannot repair itself once it leaves.

So there are only three ways to run short:

• A missing part. Iron, B12, folate. The factory is willing and the delivery is late.
• A missing signal. No erythropoietin, as in kidney disease, or a signal drowned out by inflammation.
• Loss outrunning output. Bleeding or early destruction faster than the marrow can replace. A healthy marrow can raise its output several times over, but not overnight.

Say it this way: "Anemia is a number. The diagnosis is where the circuit broke."

Iron is a closed recycling loop with a small top-up. Macrophages in the spleen and liver take apart old red cells and hand back 20 to 25 mg of iron a day, more than nine-tenths of what the marrow needs. Diet adds only 1 to 2 mg.

Iron has one door out of a cell: ferroportin. The liver makes hepcidin, and hepcidin closes that door on the gut cell and on the macrophage at the same time.

• Hepcidin rises with inflammation (IL-6) and with iron loading.
• It falls with iron need, low oxygen, and an active marrow, which releases erythroferrone to push it down.

So inflammation starves the marrow without removing a single atom. Iron piles up inside gut cells and macrophages, ferritin rises, plasma iron falls, and the marrow goes hungry next to a full warehouse.

Iron leaves the body by a short list of routes: bleeding (menstrual loss included), shed gut and skin cells in tiny amounts, pregnancy and breastfeeding (roughly a gram across a pregnancy), and urine in chronic intravascular hemolysis. That is why ordinary hemolysis in the spleen does not make anyone iron deficient, and a slow gut bleed does.

Hemostasis runs in four moves, in order:

• Plug. Within seconds, platelets stick to exposed collagen through von Willebrand factor, activate, and pile up.
• Mesh. Tissue factor on the injured wall starts the cascade. Thrombin turns fibrinogen into fibrin, which binds the plug into something that holds.
• Brakes. Antithrombin, protein C and protein S, and a healthy vessel lining keep the clot where the injury is.
• Clearance. Plasmin dissolves the fibrin once the wall has healed. D-dimer is the receipt.

Bleeding is the plug or the mesh failing. Thrombosis is the brakes losing. A patient can do both at once when the whole system is used up in small vessels, which is what disseminated intravascular coagulation is.

Virchow named the three triggers: a damaged wall, slow or stagnant flow, and blood primed to clot. Which one dominates decides what the clot is made of.

• Artery. Fast flow over a ruptured plaque. Platelets do most of the work, so the clot is platelet-rich. The long-term guard is an antiplatelet.
• Vein. Slow flow in legs that are not moving, or blood primed by cancer, estrogen, pregnancy, or an inherited defect. Fibrin and trapped red cells dominate. The guard is an anticoagulant.

That is why aspirin is a weak tool against venous clot, and why the drug after a stent is different from the drug after a deep vein thrombosis.

A complete blood count gives you a dozen numbers, and two of them do most of the work. I circle them on the printout so the habit is visual before it is verbal.

• MCV is a manufacturing record. Small cells mean the marrow ran short of what fills the cytoplasm, almost always hemoglobin, so iron or globin. Large cells mean the nucleus fell behind, or the membrane picked up extra lipid. "The MCV tells you what the marrow was short of, not what the patient has."
• RDW is the spread of sizes. Wide means two populations: the cells made before the problem and the cells made after. That is why iron deficiency widens the RDW early, often before the MCV moves.
• The other lines belong to the same reading. When the platelets and white cells fall with the hemoglobin, look at the factory.

Repeat a count that contradicts the patient. Platelets clump in the EDTA tube. A cold agglutinin clumps red cells and falsely raises the MCV. A sample drawn above an IV line is diluted. The analyzer is fast and literal.

A reticulocyte is the last stage before a mature red cell, still carrying RNA. It is the marrow's reply to the anemia. A high count says the marrow sees the problem and is working, so cells are being lost or destroyed downstream. A low count says the marrow is not replying: the lesion is in the factory or its supply.

A reported percentage is a fraction of a shrinking denominator, so anemia inflates it. Correct it before you trust it:

• Corrected reticulocyte % = reticulocyte % × (patient hematocrit ÷ 45)
• Reticulocyte production index = corrected % ÷ maturation factor (1.0 at hematocrit 45, 1.5 at 35, 2.0 at 25, 2.5 at 15)
• An index above 2 to 3 is an adequate response. Below 2 is a marrow that is not keeping up.

Simpler still, use the absolute reticulocyte count: above roughly 100 × 10⁹/L is a marrow that is answering. After a bleed, the count takes 2 to 3 days to climb.

Say it this way: "Retics don't diagnose anything. They tell you which half of the differential to open."

The smear is the cheapest consult in medicine. Ask for one whenever the indices and the patient disagree.

Fragments with a falling platelet count is an emergency until proven otherwise.

• Ferritin is the warehouse, but it is also an acute-phase reactant, so inflammation lifts it. Under 15 ng/mL is essentially diagnostic of iron deficiency. Under 30 is the practical cutoff in a patient who is not inflamed. In an inflamed patient, a ferritin under 100 does not exclude deficiency. When the question is a hidden gut cause, the AGA uses 45.
• Transferrin saturation is iron in transit. Low saturation with low ferritin is an empty store. Low saturation with high ferritin is a shut gate. Saturation alone does not separate them.
• TIBC rises when stores are empty, because the body makes more transferrin to catch every atom. It falls in inflammation.
• B12 has a grey zone, roughly 200 to 300 pg/mL. Methylmalonic acid and homocysteine show what the cell is doing: B12 deficiency raises both; folate deficiency raises only homocysteine.

Check B12 before you replace folate. The reason is in 6.4.2.

Four markers move together: LDH up, haptoglobin down, indirect bilirubin up, reticulocytes up. A haptoglobin under 25 mg/dL is highly specific.

Ask what the haptoglobin actually did. It bound free hemoglobin and was cleared with it, so it is low because it was used up, not because the liver stopped making it. It is also an acute-phase reactant, so in an inflamed patient a "normal" haptoglobin can hide brisk hemolysis.

Then ask where the cell died:

• In the vessel: haptoglobin to zero, hemoglobin in the urine, very high LDH, fragments if microangiopathic.
• In the spleen: spherocytes, jaundice, a larger spleen, less dramatic LDH. Send a direct antiglobulin test (DAT).

The trap is the panel that looks like hemolysis with low reticulocytes. That is death inside the marrow: megaloblastic anemia or myelodysplasia. Send B12, folate, methylmalonic acid and a smear before a DAT.

• PT and INR time the extrinsic and common arms (factor VII and below). Warfarin, vitamin K deficiency, and liver disease prolong them.
• aPTT times the intrinsic and common arms (factors VIII, IX, XI, XII). Heparin, hemophilia, and lupus anticoagulant prolong it.
• The mixing study asks one question when a time is long and unexplained: is something missing, or is something blocking? Mix patient plasma with normal plasma. If it corrects, a factor was missing. If it does not, an inhibitor is present, such as a lupus anticoagulant or an acquired factor VIII inhibitor.

A long time is not a bleeding tendency. Factor XII deficiency prolongs the aPTT and never bleeds. Lupus anticoagulant prolongs it and clots. The INR in cirrhosis is not a measure of bleeding risk; Chapter 5 owns that.

Platelet function, most von Willebrand disease, and factor XIII deficiency are invisible to both tests. The history finds them (6.5.4).

Two small-cell clues that cost nothing:

• Thalassemia trait keeps a normal or high red cell count, because the marrow has everything it needs and simply builds small cells. The Mentzer index (MCV ÷ RBC count) under 13 points to trait; over 13 to iron deficiency.
• A normal RDW in a microcytic patient often means lifelong.

Cell size sorts; it does not diagnose. Iron plus B12 deficiency, common after bariatric surgery or with malabsorption, averages small and large cells into a normal MCV. The RDW is wide and the smear shows both.

Once hemolysis is established (6.2.5), there are three ways a cell dies early:

• Antibody. Warm autoimmune hemolysis (IgG, spherocytes, DAT positive for IgG): idiopathic, lymphoma, lupus, drugs. Cold agglutinin disease (IgM and complement, DAT positive for C3): mycoplasma, EBV, lymphoproliferative disease. A delayed transfusion reaction belongs here too.
• A defenseless cell. Hereditary spherocytosis. G6PD deficiency after an oxidant (dapsone, primaquine, fava beans, infection) with bite cells. Sickle cell disease. Paroxysmal nocturnal hemoglobinuria, where complement destroys cells that lack their shield.
• Mechanical shear. Microangiopathy (TTP, HUS, DIC, malignant hypertension, HELLP) and mechanical valves. Fragments on the smear.

The DAT splits immune from not. The smear splits the rest. Establish hemolysis before ordering the panel that explains it.

First, check the tube. Platelets clump in EDTA in some people and the analyzer counts clumps as one. Repeat in a citrate tube and look at the smear before you work up a number that may not exist.

Then sort by mechanism:

• Made less: B12 or folate deficiency, alcohol, chemotherapy, marrow infiltration, myelodysplasia.
• Destroyed: immune thrombocytopenia (ITP), drugs, heparin-induced thrombocytopenia (HIT), infection. ITP is a diagnosis of exclusion; check HIV and hepatitis C.
• Trapped: a large spleen from portal hypertension.
• Used up: DIC, TTP and HUS, massive bleeding.

Two questions you answer today: are there fragments (6.7.2), and was there heparin in the last 5 to 10 days (6.6.5)? In pregnancy, add gestational thrombocytopenia (mild, late) and HELLP (not mild).

A high white count is usually the marrow answering: infection, steroids (which release neutrophils from the vessel walls), smoking, stress, a missing spleen. The smear is the arbiter. Toxic granulation and a left shift are an answer. Blasts are not. A steady, monotonous lymphocytosis in an older adult suggests chronic lymphocytic leukemia.

A low neutrophil count has a long benign list: drugs, recent viral illness, and Duffy-null associated neutrophil count, a normal variant common in people of African and Middle Eastern ancestry. It is not a disease, and it should not keep anyone off a drug or out of a trial. An absolute count under 500 with fever is an emergency (6.6.6).

Eosinophils: drugs, allergy, parasites. Test for strongyloides before steroids in anyone who could carry it.

Pancytopenia means the factory is failing or being bypassed: B12 or folate, alcohol, drugs, a large spleen, HIV, aplastic anemia, or a marrow filled with something else. Smear, reticulocytes, B12 and folate, and an early call to hematology about the marrow.

• Erythrocytosis. First ask whether the plasma is low (dehydration, diuretics). Then signal answered or switch stuck on. Answered: low oxygen (COPD, sleep apnea, altitude), smoking and carbon monoxide, testosterone, SGLT2 inhibitors, a tumor making erythropoietin (kidney, liver). Stuck on: polycythemia vera, driven by a JAK2 mutation in about 95% of cases, with a low erythropoietin level. The EPO level splits the two.
• Thrombocytosis. Reactive causes (iron deficiency, inflammation, infection, recovery, no spleen) are far more common than essential thrombocythemia (JAK2, CALR, MPL). Fix the iron and recheck before you call it a neoplasm.
• High ferritin. Inflammation, liver disease, alcohol, metabolic syndrome, kidney disease, and malignancy all raise it. Check the transferrin saturation. Over 45% earns testing for hereditary hemochromatosis (HFE). Under it, look for the inflammation, not the iron.

Two patterns, and the history usually tells them apart before any test:

• Surface, now. Platelet or vessel-wall problems: petechiae, gum bleeding, nosebleeds, heavy menses, bleeding right after a cut or extraction. Von Willebrand disease (the most common inherited bleeding disorder: up to about 1 in 100 people carry a lab abnormality, far fewer bleed), ITP, antiplatelet drugs, uremia.
• Depth, later. Factor problems: bleeding into joints and muscle, bleeding that starts hours after a procedure. Hemophilia A and B, warfarin, liver disease, and the one to remember in an older adult: an acquired factor VIII inhibitor, with sudden large bruises and an isolated long aPTT that does not correct on mixing.

Heavy menstrual bleeding since the first period is the most missed bleeding history in primary care. Ask, and believe the answer.

Find the trigger first: surgery, hospitalization, immobility, cancer, estrogen, pregnancy, long travel, injury. The trigger sets the duration (6.6.3).

Inherited thrombophilia testing (factor V Leiden, the prothrombin variant, protein C, protein S, antithrombin) rarely changes treatment after a first clot, and testing at the wrong time misleads: protein C, protein S and antithrombin fall during an acute clot and on warfarin or heparin.

Test when the result changes what you do:

• Antiphospholipid syndrome after an unprovoked clot, an arterial clot in a young patient, or recurrent pregnancy loss. A triple-positive patient does better on warfarin than on a DOAC.
• Unusual sites (brain sinuses, splanchnic veins): think paroxysmal nocturnal hemoglobinuria and a myeloproliferative neoplasm (JAK2).
• A relative's known defect when it would change a contraception or pregnancy plan.

After an unprovoked clot, age-appropriate cancer screening is enough. A whole-body scan finds more incidentalomas than cancers.

One plasma cell clone makes one protein, and the electrophoresis shows one spike.

• MGUS is the clone without damage: M-protein under 3 g/dL, clonal plasma cells under 10%, no organ injury. It progresses at about 1% a year, for life, so it is a follow-up plan, not a diagnosis to forget.
• Myeloma is the clone causing damage, remembered as CRAB: high Calcium, Renal injury, Anemia, Bone lesions. A very large clone (60% or more plasma cells, a free light chain ratio of 100 or more, or more than one lesion on MRI) counts too, even before damage.

Order SPEP with immunofixation and serum free light chains together. Electrophoresis alone misses light-chain disease.

Primary care clues: anemia with rouleaux, a high total protein with a normal albumin, unexplained kidney injury, new back pain in an older adult, high calcium.

Oral iron works when the gate is open. One 325 mg ferrous sulfate tablet carries about 65 mg of elemental iron. Each dose raises hepcidin for about a day, so a single dose every other day is absorbed better than daily dosing and is easier on the gut. Take it with water or vitamin C, away from tea, coffee, calcium, and antacids.

Expect reticulocytes to rise within about a week and hemoglobin to climb about 1 g/dL in the first few weeks. Continue for about three months after the hemoglobin normalizes to refill the store.

IV iron bypasses the gut and the gate. Use it for intolerance or failure of oral iron, malabsorption (celiac disease, bariatric surgery), loss that outruns oral replacement, dialysis-dependent kidney disease, and heart failure with iron deficiency. Watch for rare hypersensitivity, and for low phosphate with some products, which can soften bone with repeated doses.

B12. Pernicious anemia removes intrinsic factor, but about 1% of a large oral dose crosses the gut without it. So 1,000 to 2,000 mcg by mouth daily works for most people. Use injections when there are neurologic signs, severe deficiency, or a reason to doubt absorption or adherence. Metformin and long-term acid suppression lower B12 over years; check it in long-term metformin users, especially with neuropathy.

Folate. 1 mg daily. Never alone until B12 is known.

Why: B12 has two jobs. One it shares with folate, the step that makes DNA. The other is B12's alone, in the mitochondrion, and it keeps myelin intact. Folate rescues only the shared step. Give folate to a B12-deficient patient and the hemoglobin comes up beautifully while the spinal cord keeps degenerating.

An ESA replaces the erythropoietin a failing kidney stopped making. It works slowly, over weeks, and it does not work without iron: replete iron first, and keep it replete (KDIGO suggests iron when saturation is 30% or below and ferritin 500 or below).

The target is avoiding transfusion and symptoms, not a normal number. Trials that aimed for a normal hemoglobin found more strokes, clots, and cardiovascular events, and the drugs carry a boxed warning. Most clinicians start below 10 g/dL and stay at or under about 11.

In cancer, ESAs can shorten survival or speed tumor growth. They are limited to anemia from chemotherapy, and the decision is shared with the oncologist and the patient.

An anticoagulant stops a clot from growing and stops new ones forming. The body's own plasmin dissolves what is there, over weeks.

Choose by the patient, not the formulary:

• Kidney function and its trend.
• Weight: apixaban and rivaroxaban work for venous clot across body sizes.
• Pregnancy: low-molecular-weight heparin. Warfarin and DOACs are avoided.
• Cancer: LMWH or a DOAC; edoxaban and rivaroxaban bleed more in gut and urinary tract cancers.
• Interactions: strong inducers (rifampin, carbamazepine, phenytoin) drain DOAC levels.
• Reliability: a missed DOAC dose loses protection within a day.

Chapter 1 owns the choice in atrial fibrillation.

Reversal invites clot. The patient was anticoagulated for a reason, and that reason does not leave when the bleeding starts. Keep reversal for bleeding that threatens life or an organ: inside the skull, into a closed space, or hemorrhage that does not respond to resuscitation. For many gut bleeds, holding the drug and supporting the patient is enough; with normal kidneys, a DOAC fades within a day or two.

Availability of specific antidotes changes. Know what your hospital stocks before you need it.

A platelet has no nucleus and cannot make new enzyme. Aspirin disables COX-1 for the platelet's whole life, about 7 to 10 days. Clopidogrel and prasugrel block the P2Y12 receptor permanently; ticagrelor reversibly, but still for days. "Hold the aspirin for two days" does almost nothing.

Antiplatelets are the long-term guard after a heart attack, an atherosclerotic stroke, a stent, or peripheral artery disease. Two antiplatelets, or an antiplatelet plus an anticoagulant, multiply bleeding: every added drug should have a stop date written down.

For primary prevention, aspirin now does more harm than good for most older adults. The USPSTF recommends against starting it at 60 and over.

Never stop dual antiplatelet therapy early after a stent without the cardiologist.

• Blunt the attack: corticosteroids and IVIG for ITP and warm autoimmune hemolysis; rituximab when they fail.
• Out-produce it: thrombopoietin receptor agonists (romiplostim, eltrombopag) push the marrow to make platelets faster than the immune system destroys them.
• Quiet an overactive marrow: hydroxyurea in polycythemia vera and essential thrombocythemia, and to raise fetal hemoglobin in sickle cell disease.

Specialists start these. Primary care inherits what follows:

• Infection. Rituximab can reactivate hepatitis B; screen before it starts. Vaccinate before rituximab or splenectomy where you can.
• Steroid effects. Glucose, bone, mood, sleep, blood pressure.
• Clot risk. Thrombopoietin agonists, IVIG, and the underlying disease all raise it.

Pallor shows late, and best where the skin is thinnest: the lower eyelid, the palmar creases, the nail beds. Its absence does not exclude anemia.

• Pallor with jaundice: hemolysis, or ineffective erythropoiesis.
• Spoon nails, cracked mouth corners, a smooth tongue: deficiency.
• Press on the red spot. If it blanches, it is a dilated vessel. If it does not, it is blood outside the vessel. Pinpoint non-blanching petechiae in dependent areas mean platelets or the vessel wall. Raised, palpable purpura means vasculitis.
• Bruises on the trunk without trauma earn a count and a coagulation panel the same day.

The spleen enlarges down and across, toward the right iliac fossa. Start palpating low, in the right lower quadrant, and walk up toward the left costal margin as the patient breathes in. Start high and you can miss a large spleen whose edge you are already standing on.

Percuss first. Dullness in Traube's space, or at the lowest left intercostal space in the anterior axillary line on a deep breath, suggests enlargement. Ultrasound settles it.

A massive spleen has a short list: myelofibrosis, chronic myeloid leukemia, lymphoma, and in travelers, malaria and visceral leishmaniasis. Portal hypertension enlarges it more modestly and traps platelets (6.3.3).

• Tender, soft, mobile: reactive, usually infection.
• Rubbery, sometimes matted: lymphoma.
• Hard and fixed: metastatic.

A localized node with benign features can be watched for three to four weeks. Size over about 1 cm (1.5 cm in the groin), growth, or persistence earns more.

A supraclavicular node is abnormal until proven otherwise. The left one drains the abdomen; the right drains the chest. Generalized nodes send you to HIV, EBV, lupus, drugs, and lymphoma.

Use a structure, such as the ISTH Bleeding Assessment Tool, so you ask the same questions every time:

• Bleeding after dental extraction, surgery, or childbirth? Ever needed a transfusion or a return to the operating room?
• Nosebleeds: how long, both sides, ever needed packing?
• Heavy menses since the first period: flooding, large clots, changing protection hourly, iron deficiency?
• Bruising: size, place, without trauma?
• Family history.
• Every medicine and supplement: aspirin, NSAIDs, SSRIs, fish oil, ginkgo.

A negative structured history before surgery is worth more than normal screening coagulation tests, which miss von Willebrand disease and platelet defects and flag harmless factor XII deficiency.

Most serious transfusion reactions are identification errors: the right blood into the wrong patient. Two people check every unit at the bedside, against the wristband.

Start slowly and stay for the first 15 minutes, when an ABO reaction shows itself: fever, rigors, back or flank pain, low blood pressure, dark urine. Stop the transfusion first, keep the line open with saline, then call the blood bank.

The others to know:

• Febrile non-hemolytic: common, benign, a diagnosis made after the dangerous ones are excluded.
• Allergic: hives; anaphylaxis is rare.
• TACO (circulatory overload): the serious one in older patients with heart or kidney disease. Go one unit at a time, slowly, and diurese when needed.
• TRALI (lung injury): breathing worsens within six hours, without fluid overload.

• Small cells: iron studies. If the iron is gone, the next question is where it went (6.7.1).
• Normal cells: the reticulocyte count. High: bleeding or the hemolysis panel. Low: creatinine, TSH, inflammation, a smear.
• Large cells: a smear, B12 with methylmalonic acid, folate, the medicine list, alcohol, liver tests, TSH. If those are clean, think about the marrow.

The deficiency is a finding. The cause is the diagnosis.

The price on each side: acting too early buys tests and false trails. Waiting too long buys a missed colon cancer or a marrow problem found late.

For hemodynamically stable hospitalized adults, a restrictive threshold of 7 g/dL is as safe as a liberal one and spares blood (AABB 2023). Other settings differ:

Give one unit, then reassess. One unit raises hemoglobin about 1 g/dL in an average adult.

Symptoms override the number: chest pain, breathlessness at rest, fainting. And chronic, compensated anemia in clinic (iron, B12) rarely needs blood. Replace the missing part.

"Extended" is not "forever without thought." Reassess bleeding risk and the patient's wishes every year. The decision belongs in the note with a date.

The cause changes everything:

• TTP and HIT: withhold platelets unless bleeding threatens life. Transfused platelets feed the clots.
• ITP: transfused platelets are destroyed in hours. Treat when the count is under 30 or there is bleeding, with steroids and IVIG for serious bleeding. Watch when the count is above 30 and the patient is not bleeding.

Heparin-induced thrombocytopenia is a clotting disorder that happens to lower the platelet count. Antibodies against heparin and platelet factor 4 activate platelets, and clots follow, in veins and arteries.

Score the probability before you send the antibody test. A low 4Ts score (0 to 3) makes HIT very unlikely, and the test is not needed. At 4 or more:

• Stop all heparin, including flushes and low-molecular-weight heparin.
• Start a non-heparin anticoagulant (argatroban, bivalirudin, fondaparinux, or a DOAC). Stopping heparin alone is not enough; the clot risk stays high for weeks.
• Send the anti-PF4 antibody, and confirm a positive with a functional assay.
• No warfarin until the platelets recover, and reverse it with vitamin K if it was already started. No routine platelet transfusion.
• Image the legs. Silent clots are common.

Call hematology, or send the patient in, the same day for:

• Fragments with falling platelets. TTP until proven otherwise (6.7.2).
• Blasts on the smear, or a white count over 100 × 10⁹/L.
• Fever with an absolute neutrophil count under 500. Antibiotics within the hour.
• A bleed that threatens life or an organ: inside the skull, a gut bleed with unstable vital signs.
• A clot that threatens life or an organ: a large pulmonary embolism, a cold limb, a clot in the brain's venous sinuses.
• HIT with a new clot.
• Sickle cell disease with chest syndrome, stroke signs, priapism, or a rapidly enlarging spleen.
• A paraprotein with high calcium or acute kidney injury.

Hematologists would rather hear a false alarm at noon than a true one at midnight.

• Restart a DOAC about 1 day after a low-risk procedure and 2 to 3 days after a high-risk one, once bleeding is controlled.
• No bridging for DOACs. They come and go quickly on their own.
• Bridging warfarin is for the highest clot risk only: a mechanical mitral valve, a stroke or venous clot in the last three months. In atrial fibrillation, bridging added bleeding without preventing strokes.
• Many minor procedures (most dental work, cataract surgery, skin biopsies) go ahead without stopping at all.

Some patients decline blood, many of them Jehovah's Witnesses. Treat it as informed refusal, the same way you would any other:

• Confirm capacity, and have the conversation in private, without family in the room to pressure either way.
• Explain the risk plainly, including what could happen without blood.
• Ask which components, not which faith. Many accept some fractions (albumin, clotting factor concentrates, immunoglobulins) or their own blood kept in a continuous circuit (cell salvage, dialysis), and decline red cells, white cells, platelets, and plasma. The answer is individual.
• Plan before it is urgent: treat iron deficiency early, draw small tubes, consider tranexamic acid and ESAs, and record the decision in an advance directive.

For children, the law is different. Involve the ethics team and legal counsel early, not at the bedside at 2 a.m.

A pain crisis in sickle cell disease is real ischemic pain. People with sickle cell disease wait longer for pain treatment than others with similar pain, and they are labeled "drug-seeking" for asking for the dose that has worked before.

National guidance calls for the first dose within about an hour of arrival, and reassessment every 15 to 30 minutes. The tool that changes the visit is a plan made in advance:

• Write the plan in clinic, when nobody is in pain: which medicine, dose, route, what has worked, who to call.
• Share it with the emergency department and put it where the triage nurse will see it.
• Screen for the emergencies hiding inside a pain visit: chest syndrome, stroke, priapism, splenic sequestration.
• Offer hydroxyurea to most adults with HbSS disease.

Words matter. "A person with sickle cell disease," never "a sickler."

Sickle trait, thalassemia trait, hemochromatosis, factor V Leiden: one person's result is information about parents, siblings, and children.

• Offer cascade testing, explain what it would change for each relative, and offer help with the conversation, or a letter they can share.
• The patient decides whether and when to tell. Your job is to make it easy, not to do it for them.
• Before testing, say plainly what US law protects. GINA bars genetic discrimination in health insurance and employment. It does not cover life, disability, or long-term care insurance.
• Sickle trait matters for reproductive planning and for rare complications with extreme exertion and dehydration. It is not a disease.

A DOAC's effect is largely gone a day after a missed dose. The trial results only hold for the patient who takes it.

• Cost is the most common reason doses are skipped or prescriptions never filled. Medicare's negotiated prices for apixaban and rivaroxaban took effect January 1, 2026; what a given patient pays still depends on their plan. Ask what they pay.
• Interactions: check every new prescription. Azole antifungals, some anticonvulsants, rifampin, and some HIV drugs move DOAC levels.
• Teach the warning signs that need a call: black stools, blood in the urine, a headache unlike others, a fall with a head strike.
• Make it easy: a pill organizer and a phone alarm cost less than a stroke.