Understand My Lab Report

Kidney & urinary

eGFR, creatinine, albuminuria, urinalysis

Estimated GFR

eGFR · Estimated glomerular filtration rate · Kidney & urinary

What it measures: How much blood the kidneys filter per minute, estimated from creatinine (or cystatin C), age and sex.
Why it is ordered: To assess kidney function, stage CKD (G1–G5), follow the rate of change and adjust drug doses.
Unit · Example reference range: mL/min/1.73 m²
≥90 = G1; 60–89 G2; 45–59 G3a; 30–44 G3b; 15–29 G4; <15 G5 (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Muscle mass, recent heavy exercise, large meat meals, dehydration and some drugs (e.g. trimethoprim, cimetidine) change creatinine without changing true kidney function.
How to read an abnormal result: One value is not a diagnosis; CKD requires eGFR <60 or kidney-damage markers for >3 months. The trend (a fall >5 per year is rapid progression) matters more than one point.
When to ask your clinician: Ask if eGFR fell >5 since last time, is <60 for the first time, or is abnormal together with albuminuria — whether to repeat, look for a cause or see a nephrologist.
Preparation: Avoid heavy exercise and large red-meat meals for 24 h; drink normally.

CKD Staging Explained: The Five KDIGO GFR Categories and Three Albuminuria Grades What Is Kidney Disease? Acute Kidney Injury vs. Chronic Kidney Disease Calcolatore eGFR Diario di Monitoraggio della Funzione Renale (eGFR)腎臟檢驗數值追蹤時間軸

Serum creatinine

Cr / sCr · Serum creatinine · Kidney & urinary

What it measures: A muscle-metabolism waste product cleared by the kidneys.
Why it is ordered: The main input for eGFR; used to follow kidney function.
Unit · Example reference range: mg/dL（或 µmol/L；×88.4）
Adults roughly 0.6–1.2 mg/dL, slightly higher in men (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Higher with more muscle, lower with sarcopenia; dehydration, hard exercise and high-protein meals raise it briefly.
How to read an abnormal result: A "normal" creatinine does not guarantee normal kidney function (older or frail people may already have CKD); always look at the eGFR.
When to ask your clinician: A rise ≥0.3 mg/dL within 48 h or ≥1.5× baseline may be acute kidney injury — seek care promptly.
Preparation: As for eGFR.

CKD Staging Explained: The Five KDIGO GFR Categories and Three Albuminuria Grades Calcolatore eGFR 腎臟檢驗數值追蹤時間軸

Urine albumin-creatinine ratio

UACR / ACR · Urine albumin-to-creatinine ratio · Kidney & urinary

What it measures: Albumin relative to creatinine in a spot urine sample — whether the kidney filters are leaking protein.
Why it is ordered: The second axis of CKD staging (A1–A3); annual screening in diabetes and hypertension; cardiovascular risk and response to ACEi/ARB or SGLT2 inhibitors.
Unit · Example reference range: mg/g（或 mg/mmol；÷8.84）
<30 A1 normal–mildly increased; 30–300 A2 moderate; >300 A3 severe (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Exercise, fever, infection, menstruation, prolonged standing and very high glucose can raise it temporarily.
How to read an abnormal result: Persistent albuminuria needs 2 of 3 abnormal results within 3 months; a first-morning sample is most reliable.
When to ask your clinician: If ≥30 mg/g for the first time, ask about repeating within 3 months and whether blood-pressure or glucose medicines should change.
Preparation: First-morning urine is best; avoid hard exercise for 24 h.

CKD Staging Explained: The Five KDIGO GFR Categories and Three Albuminuria Grades 腎友的血壓：為什麼目標是「<120」、在家怎麼量才算數、ACEi/ARB 為什麼不能因為一次正常就停 Interpretazione UACR (proteine urinarie)

Urinalysis

UA · Urinalysis (dipstick + microscopy) · Kidney & urinary

What it measures: Specific gravity, pH, protein, glucose, blood, leucocytes, nitrite, and red/white cells and casts under the microscope.
Why it is ordered: Screening for urinary infection, haematuria, proteinuria and clues to glomerulonephritis.
Unit · Example reference range: 定性（−／±／1+～4+）
Protein, glucose, blood and nitrite are usually negative (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Menstruation, hard exercise, dehydration and high-dose vitamin C cause false positives/negatives.
How to read an abnormal result: Dipstick protein ≥1+ should be quantified with UACR; persistent microscopic haematuria needs a cause.
When to ask your clinician: Ask about nephrology referral if haematuria occurs with proteinuria or red-cell casts.
Preparation: Mid-stream sample; avoid menstruation.

What Is Kidney Disease? Acute Kidney Injury vs. Chronic Kidney Disease Interpretazione UACR (proteine urinarie)

Blood count & anaemia

Haemoglobin, ferritin, white cells, platelets

Haemoglobin

Hb / Hgb · Haemoglobin · Blood count & anaemia

What it measures: The oxygen-carrying protein in red cells.
Why it is ordered: To diagnose anaemia; in CKD, anaemia from low erythropoietin is common.
Unit · Example reference range: g/dL
WHO anaemia: men <13, non-pregnant women <12 (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Dehydration raises it; pregnancy, recent bleeding and fluid shifts after dialysis change it.
How to read an abnormal result: Before treating CKD anaemia, rule out iron deficiency (ferritin, TSAT); ESA targets are usually 10–11.5 g/dL, not "normal".
When to ask your clinician: If Hb <10 or falls >1 g/dL quickly, ask about iron studies, occult blood and treatment changes.
Preparation: No fasting needed.

腎性貧血完整指南：為什麼腎友容易貧血？先補鐵還是先打針？HIF 口服新藥是什麼？腎臟檢驗數值追蹤時間軸

Ferritin & TSAT

Ferritin / TSAT · Ferritin and transferrin saturation · Blood count & anaemia

What it measures: Ferritin = stored iron; TSAT = iron available in the blood.
Why it is ordered: To tell whether anaemia is from iron deficiency and whether oral or IV iron is needed.
Unit · Example reference range: ng/mL；%
General iron deficiency: ferritin <30; in CKD/dialysis, iron is often considered when ferritin ≤500 and TSAT ≤30% (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Ferritin rises falsely with inflammation, infection and liver disease; TSAT is then more informative.
How to read an abnormal result: A "normal" ferritin does not exclude functional iron deficiency; read it with CRP.
When to ask your clinician: If on ESA but Hb is not rising, ask whether iron should come first.
Preparation: No fasting; avoid testing during infection.

腎性貧血完整指南：為什麼腎友容易貧血？先補鐵還是先打針？HIF 口服新藥是什麼？

Complete blood count

CBC · Complete blood count · Blood count & anaemia

What it measures: Numbers and sizes of red cells, white cells (with differential) and platelets.
Why it is ordered: General check-up; monitoring infection, anaemia, bleeding tendency and drug effects (e.g. immunosuppressants).
Unit · Example reference range: ×10³/µL；fL
WBC ~4–10; platelets ~150–400; MCV ~80–100 fL (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Exercise, stress and steroids raise WBC; low MCV suggests iron deficiency, high MCV suggests B12/folate deficiency or alcohol.
How to read an abnormal result: In transplant recipients a low WBC should be checked against drugs such as mycophenolate or valganciclovir.
When to ask your clinician: Return promptly if WBC <3 or platelets <100 without an obvious reason.
Preparation: No fasting needed.

腎性貧血完整指南：為什麼腎友容易貧血？先補鐵還是先打針？HIF 口服新藥是什麼？移植後最常見的癌症是皮膚癌：風險有多高、每天怎麼防曬、什麼樣的斑點要立刻就醫

Liver & digestive

ALT/AST, bilirubin, albumin, FIB-4, hepatitis B/C

Liver enzymes ALT/AST

ALT / AST · Alanine & aspartate aminotransferase · Liver & digestive

What it measures: Enzymes released into the blood when liver cells are injured.
Why it is ordered: Screening for fatty liver, viral hepatitis and drug-induced injury; monitoring liver disease and drugs such as statins, TB drugs and immunosuppressants.
Unit · Example reference range: U/L
ALT upper limit often ~30–40 (men), 19–35 (women); varies widely by lab (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Hard exercise (AST also comes from muscle), alcohol, obesity and some supplements/herbal products raise them.
How to read an abnormal result: Mild rises (<3× ULN) are usually fatty liver; AST>ALT with ratio >2 suggests alcohol; assess fibrosis with bilirubin, albumin and platelets (FIB-4).
When to ask your clinician: If ALT >3× ULN or with jaundice/fatigue, seek care soon and list every medicine and supplement you take.
Preparation: Avoid alcohol and hard exercise for 48 h.

Fatty Liver Is More Than "Fat in the Liver": The MASLD Rename, How to Calculate FIB-4, Who Needs Fibrosis Testing, and How Much Weight Loss Works 查核：「吃保肝片（奶薊、朝鮮薊、薑黃）可以保護肝臟、降肝指數」有多少證據？ Indice FIB-4 di Fibrosi Epatica

FIB-4 index

FIB-4 · Fibrosis-4 index · Liver & digestive

What it measures: A fibrosis-risk score from age, AST, ALT and platelets.
Why it is ordered: First-line triage in fatty liver: who needs elastography or hepatology referral.
Unit · Example reference range: 分數
<1.3 low risk (<2.0 if ≥65 y); 1.3–2.67 indeterminate; >2.67 high (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Acute hepatitis, low platelets from other causes and age >65 reduce accuracy.
How to read an abnormal result: A rule-out tool: a low score is reassuring; a high score is not cirrhosis but needs further testing.
When to ask your clinician: If FIB-4 ≥1.3 ask about a fibrosis scan (FibroScan / elastography).
Preparation: Calculate from the same day's blood results.

Fatty Liver Is More Than "Fat in the Liver": The MASLD Rename, How to Calculate FIB-4, Who Needs Fibrosis Testing, and How Much Weight Loss Works Indice FIB-4 di Fibrosi Epatica

Hepatitis B & C screening

HBsAg / anti-HCV · Hepatitis B surface antigen; hepatitis C antibody · Liver & digestive

What it measures: HBsAg positive = current hepatitis B infection; anti-HCV positive = past exposure to hepatitis C — HCV RNA confirms active infection.
Why it is ordered: Required before dialysis and transplant; reactivation risk before immunosuppression or chemotherapy; at least once in all adults.
Unit · Example reference range: 陰性／陽性
Negative = not infected (for HBV also check anti-HBs for immunity)
What can skew the result: anti-HBs positive after vaccination is normal; anti-HCV stays positive after cure.
How to read an abnormal result: HBsAg carriers need regular HBV DNA and ultrasound even with normal liver enzymes.
When to ask your clinician: If HBsAg positive and about to start immunosuppressants/biologics, ask about prophylactic antivirals.
Preparation: No fasting needed.

What Hepatitis B Carriers Should Know: What to Monitor, When to Start Antivirals, and Why Immunosuppression (Including Dialysis and Transplant) Can Reactivate the Virus

Glucose, lipids & metabolic

HbA1c, fasting glucose, LDL, uric acid, TSH

HbA1c

HbA1c · Glycated haemoglobin · Glucose, lipids & metabolic

What it measures: Average blood glucose over the past 2–3 months.
Why it is ordered: To diagnose and follow diabetes and set targets.
Unit · Example reference range: %（或 mmol/mol）
<5.7 normal; 5.7–6.4 prediabetes; ≥6.5 diabetes. Usual target <7, relaxed for older/multimorbid adults (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Anaemia, transfusion, ESA therapy, dialysis and haemoglobin variants make HbA1c unreliable — especially in CKD G4–5 and dialysis.
How to read an abnormal result: In kidney patients HbA1c may underestimate true glucose; consider CGM or glycated albumin.
When to ask your clinician: If HbA1c disagrees with your home glucose readings, ask whether anaemia or dialysis is affecting it.
Preparation: No fasting needed.

Type 2 Diabetes Guide: Why HbA1c Targets Differ by Person, Choosing Medication in 2025, the Kidney Tests You Need Every Year, and Handling Hypoglycaemia 查核：「糖尿病前期遲早會變成糖尿病，做什麼都沒用」是真的嗎？ Conversione HbA1c ↔ Glicemia Media

Fasting glucose

FPG · Fasting plasma glucose · Glucose, lipids & metabolic

What it measures: Blood glucose after an 8-hour fast.
Why it is ordered: Screening and diagnosis of diabetes; complements HbA1c.
Unit · Example reference range: mg/dL（或 mmol/L；÷18）
<100 normal; 100–125 impaired fasting glucose; ≥126 (twice) diabetes (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Not truly fasting, stress, infection, steroids and poor sleep raise it.
How to read an abnormal result: One abnormal result should be confirmed on another day or with HbA1c.
When to ask your clinician: See your clinician soon if ≥126 or if you have thirst, frequent urination or weight loss.
Preparation: Fast 8–12 h (water allowed); ask beforehand whether to take usual medicines.

Type 2 Diabetes Guide: Why HbA1c Targets Differ by Person, Choosing Medication in 2025, the Kidney Tests You Need Every Year, and Handling Hypoglycaemia Conversione HbA1c ↔ Glicemia Media

Lipid panel

LDL-C / HDL-C / TG · Lipid panel · Glucose, lipids & metabolic

What it measures: Blood cholesterol and triglycerides; LDL is the main driver of atherosclerosis.
Why it is ordered: To estimate cardiovascular risk and decide on statins; CKD itself is high-risk.
Unit · Example reference range: mg/dL
LDL target depends on risk: general <130; high <100; very high <70 or <55 (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Triglycerides vary a lot with the last meal and alcohol; LDL can be measured non-fasting.
How to read an abnormal result: In dialysis the benefit of statins is weaker (KDIGO: continue if already on, do not start); transplant recipients are advised to use them.
When to ask your clinician: Triglycerides >500 risk pancreatitis — act promptly.
Preparation: Fast 9–12 h if triglycerides matter.

Heart Failure Explained: Ejection Fraction, the Four Pillars of Treatment, Why You Weigh Yourself Daily, and the Kidney Dilemma 查核：「每天吃魚油膠囊可以預防心臟病」有多少證據？

Uric acid

UA / sUA · Serum uric acid · Glucose, lipids & metabolic

What it measures: The end product of purine metabolism, cleared by the kidneys.
Why it is ordered: To assess gout risk and urate-lowering targets; often raised in CKD.
Unit · Example reference range: mg/dL
Common upper limits: men <7, women <6; gout treatment target <6 (<5 with tophi) (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Diuretics, low-dose aspirin, alcohol (especially beer), fructose drinks and dehydration raise it; during an acute flare it can be normal.
How to read an abnormal result: Asymptomatic hyperuricaemia is generally not treated with drugs alone; treatment depends on flares, tophi and kidney stones.
When to ask your clinician: With ≥2 flares a year or tophi, ask about urate-lowering therapy dosed for your kidney function.
Preparation: Strict fasting not needed; avoid heavy drinking the night before.

Gout and High Uric Acid: Treating a Flare, How Low Urate Should Go, Using Allopurinol Correctly, and Which Drugs to Avoid with Kidney Disease

Thyroid function (TSH, FT4)

TSH / FT4 · Thyroid-stimulating hormone; free thyroxine · Glucose, lipids & metabolic

What it measures: TSH is the pituitary's signal to the thyroid (most sensitive); FT4 is the hormone the thyroid actually makes.
Why it is ordered: Work-up of fatigue, weight change, palpitations, bowel changes; monitoring amiodarone, lithium and immunotherapy.
Unit · Example reference range: mIU/L；ng/dL
TSH ~0.4–4.0; high TSH + low FT4 = hypothyroid; low TSH + high FT4 = hyperthyroid (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Acute illness, steroids and biotin supplements interfere; TSH may be mildly raised in CKD.
How to read an abnormal result: TSH 4–10 with normal FT4 is subclinical hypothyroidism — usually re-check in 6–12 weeks first.
When to ask your clinician: Ask about treatment if pregnant, planning pregnancy or TSH >10.
Preparation: Stop biotin 2 days before; take levothyroxine after the blood draw.

Thyroid Disorders: Reading Your TSH, Symptoms and Treatment of Under- and Over-active Thyroid, and Why Thyroid Tests Often Look "Odd" in CKD

Electrolytes & minerals

Potassium, sodium, calcium, phosphate, PTH

Potassium

K⁺ · Serum potassium · Electrolytes & minerals

What it measures: Potassium in the blood, which affects heart rhythm and muscles.
Why it is ordered: Essential monitoring in CKD, dialysis and with ACEi/ARB/MRA or potassium-sparing diuretics.
Unit · Example reference range: mEq/L (mmol/L)
~3.5–5.0; >5.5 hyperkalaemia, >6.0 an emergency (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Prolonged fist clenching, haemolysis and very high platelets cause false elevation; values differ a lot before vs after dialysis.
How to read an abnormal result: Hyperkalaemia is often silent; do not stop ACEi/ARB yourself after one high value — discuss diet, diuretics or potassium binders.
When to ask your clinician: K ≥6.0, or ≥5.5 with weakness/palpitations: seek care immediately.
Preparation: Relax the arm; do not pump the fist.

腎友廚房：低鉀、低磷、低鈉的日常飲食實戰 Fact check: "Every kidney patient must strictly limit potassium — no bananas, tomatoes or potatoes." Is that true? Tabella Rapida Potassio · Fosforo · Calcio Calcolatore della Dieta per Malattia Renale

Sodium

Na⁺ · Serum sodium · Electrolytes & minerals

What it measures: Blood sodium, which mainly reflects body water balance rather than salt intake.
Why it is ordered: To assess dehydration, fluid overload, diuretic effects and heart failure / cirrhosis / SIADH.
Unit · Example reference range: mEq/L
~135–145 (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: High glucose or lipids cause pseudohyponatraemia; thiazides and some antidepressants lower sodium.
How to read an abnormal result: Sodium <125 or rapid change can alter consciousness; correction must be paced by a clinician — too fast is dangerous.
When to ask your clinician: Headache, nausea or confusion with low sodium: seek care immediately.
Preparation: No fasting needed.

Heart Failure Explained: Ejection Fraction, the Four Pillars of Treatment, Why You Weigh Yourself Daily, and the Kidney Dilemma

Calcium, phosphate & PTH

Ca / P / PTH · Calcium, phosphate, parathyroid hormone · Electrolytes & minerals

What it measures: The three CKD-MBD markers: calcium, phosphate and the hormone (PTH) that regulates them.
Why it is ordered: Routine from CKD G3 onward; guides phosphate binders, active vitamin D and calcimimetics.
Unit · Example reference range: mg/dL；pg/mL
Phosphate commonly 2.5–4.5; dialysis PTH target roughly 2–9× the upper limit (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Calcium must be corrected for albumin; phosphate depends on the last meal and dialysis timing.
How to read an abnormal result: Follow the trend, not one value; high phosphate links to vascular calcification and mortality, but over-restriction causes malnutrition.
When to ask your clinician: If PTH keeps rising or calcium is high, ask about adjusting vitamin D / calcimimetics or evaluating the parathyroid glands.
Preparation: In dialysis, pre-dialysis samples are the standard.

Which Phosphate Binders Are Available? A Comparison of Options in Taiwan, and When Parathyroid Surgery Is Advised Osteoporosis: Reading Your T-score, Calculating FRAX, Which Drugs Actually Prevent Fractures, and Why Kidney Disease Changes the Rules Tabella Rapida Potassio · Fosforo · Calcio

Cardiovascular tests

Blood pressure, ECG, BNP, echocardiography

Blood pressure

BP · Blood pressure (office & home) · Cardiovascular tests

What it measures: Systolic/diastolic pressure; home readings predict risk better than clinic readings.
Why it is ordered: The most important modifiable factor for CKD progression and cardiovascular events.
Unit · Example reference range: mmHg
KDIGO 2021: standardized office systolic <120 in adults with CKD if tolerated; home <135/85 corresponds to office 140/90 (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Caffeine/smoking within 30 min, talking, a small cuff, no 5-minute rest and a full bladder all overestimate.
How to read an abnormal result: One high reading is not hypertension; use the 7-day average of two readings morning and evening.
When to ask your clinician: Home average ≥135/85, or <100/60 with dizziness: discuss medication changes.
Preparation: Seated, back supported, feet flat, arm at heart level, rest 5 minutes.

腎友的血壓：為什麼目標是「<120」、在家怎麼量才算數、ACEi/ARB 為什麼不能因為一次正常就停查核：「每天鹽吃不到 5 公克就能把血壓降下來，人人都該嚴格限鹽」是真的嗎？ Registro e Andamento della Pressione Arteriosa

Electrocardiogram

ECG / EKG · Electrocardiogram · Cardiovascular tests

What it measures: The heart's electrical activity: rhythm, atrial fibrillation, ischaemia and hyperkalaemia changes.
Why it is ordered: Work-up of palpitations, chest pain and syncope; routine before dialysis/transplant; urgent reading in hyperkalaemia.
Unit · Example reference range: 波形判讀
Sinus rhythm, rate 60–100, no acute ST changes
What can skew the result: Electrode placement, tremor and electrolyte disturbances alter the tracing.
How to read an abnormal result: Paroxysmal AF may be absent during a single ECG — consider a 24-hour Holter or wearable if symptoms persist.
When to ask your clinician: If AF is found, ask about anticoagulation (taking kidney function into account).
Preparation: No fasting; wear an easily removed top.

Atrial Fibrillation: Why It Raises Stroke Risk Fivefold, How to Score CHA₂DS₂-VA, and Choosing Anticoagulants When Kidneys Are Weak

BNP / NT-proBNP

BNP / NT-proBNP · B-type natriuretic peptide · Cardiovascular tests

What it measures: A hormone released when the heart is under strain, reflecting heart-failure severity.
Why it is ordered: To distinguish causes of breathlessness and oedema; heart-failure follow-up.
Unit · Example reference range: pg/mL
NT-proBNP <125 generally rules out HF; but baseline is higher in CKD and dialysis, so cut-offs must be raised (example range only; varies by lab, method, age and sex — use the range printed on your report)
What can skew the result: Lower kidney function, age and AF raise it; obesity lowers it.
How to read an abnormal result: Kidney patients cannot use general cut-offs directly; personal trends are more meaningful.
When to ask your clinician: If clearly above your usual level with breathlessness/oedema, see your clinician soon.
Preparation: No fasting needed.

Heart Failure Explained: Ejection Fraction, the Four Pillars of Treatment, Why You Weigh Yourself Daily, and the Kidney Dilemma

Imaging

Kidney ultrasound, low-dose CT, DXA bone density

Kidney ultrasound

Renal US · Kidney ultrasound · Imaging

What it measures: Kidney size, cortical thickness, hydronephrosis, cysts, stones and masses; no radiation.
Why it is ordered: Baseline in newly diagnosed CKD; haematuria/obstruction work-up; polycystic kidney follow-up.
Unit · Example reference range: 影像描述
Adult kidney length ~10–12 cm; bilateral shrinkage (<9 cm) suggests chronic disease
What can skew the result: Bowel gas and obesity reduce image quality; simple cysts are common with age.
How to read an abnormal result: Normal size does not exclude early CKD; complex cysts (Bosniak) need CT/MRI.
When to ask your clinician: If the report says complex cyst, mass or hydronephrosis, ask what the next test is and when.
Preparation: Usually no fasting; a full bladder if the bladder is also examined.

What Is Kidney Disease? Acute Kidney Injury vs. Chronic Kidney Disease

Low-dose CT (lung screening)

LDCT · Low-dose CT lung cancer screening · Imaging

What it measures: Finds lung nodules with ~1/5 the radiation of a standard CT.
Why it is ordered: Only recommended for eligible high-risk people (heavy smoking history, specific family history); not for everyone yearly.
Unit · Example reference range: Lung-RADS 分級
Lung-RADS 1–2 negative/benign; 3 probably benign (6-month follow-up); 4 suspicious
What can skew the result: High false-positive rate (most nodules are benign), with anxiety and possible unnecessary invasive tests.
How to read an abnormal result: A nodule is not cancer; follow-up interval depends on size and type.
When to ask your clinician: Confirm you actually meet screening criteria, and whether contrast could affect your kidneys (screening LDCT normally uses none).
Preparation: No fasting; remove metal objects.

查核：「每個人都該每年做一次低劑量電腦斷層（LDCT）篩檢肺癌」是真的嗎？

DXA bone density

DXA / T-score · Dual-energy X-ray absorptiometry · Imaging

What it measures: Bone density at spine and hip, compared with young adults as a T-score.
Why it is ordered: Osteoporosis assessment in postmenopausal women, age ≥65, long-term steroids and after transplant.
Unit · Example reference range: T 值
≥ −1 normal; −1 to −2.5 osteopenia; ≤ −2.5 osteoporosis
What can skew the result: Spinal degeneration and vascular calcification falsely raise lumbar T-scores; DXA cannot tell the type of bone disease in CKD-MBD.
How to read an abnormal result: In CKD G3–5 fracture risk needs FRAX plus PTH and alkaline phosphatase, not T-score alone.
When to ask your clinician: If T ≤ −2.5 or you have had a fragility fracture, ask whether drug choice must be adjusted for kidney function (bisphosphonates need caution below eGFR 30).
Preparation: No calcium tablets for 24 h; avoid right after a contrast study.

Osteoporosis: Reading Your T-score, Calculating FRAX, Which Drugs Actually Prevent Fractures, and Why Kidney Disease Changes the Rules 吃骨鬆藥不能拔牙？藥物相關顎骨壞死（MRONJ）的真實風險與該怎麼安排

Other specialist tests

Spirometry, sleep study, oral screening

Spirometry

FEV1 / FVC · Spirometry · Other specialist tests

What it measures: Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC), to detect airway obstruction.
Why it is ordered: Diagnosis and grading of COPD and asthma; monitoring inhaler response.
Unit · Example reference range: 比值；% 預測值
Post-bronchodilator FEV1/FVC <0.70 = obstruction (GOLD); FEV1 % predicted grades severity
What can skew the result: Poor effort, coughing and acute infection underestimate values; a trained operator matters.
How to read an abnormal result: A fixed 0.70 cut-off may over-diagnose in older adults; the lower limit of normal (LLN) is an alternative.
When to ask your clinician: If you smoke and have chronic cough or breathlessness, ask for spirometry rather than only a chest X-ray.
Preparation: Pause inhalers as instructed (short-acting 4–6 h, long-acting 12–24 h); avoid big meals and smoking.

COPD and Asthma: How to Tell Them Apart, Reading Your Spirometry, Why Inhalers "Don't Work", and an Action Plan for Flare-ups 查核：「抽了三十年菸，現在戒也來不及了」是真的嗎？

Sleep study

PSG / HSAT · AHI · Polysomnography / home sleep apnoea test · Other specialist tests

What it measures: Apnoeas and hypopnoeas per hour (AHI), oxygen levels and sleep stages.
Why it is ordered: Work-up of snoring, daytime sleepiness, resistant hypertension, heart failure and sleep apnoea in dialysis patients.
Unit · Example reference range: AHI（次／小時）
<5 normal; 5–14 mild; 15–29 moderate; ≥30 severe
What can skew the result: Home tests underestimate AHI; sleep position, alcohol and nasal congestion that night matter.
How to read an abnormal result: CPAP improves blood pressure and quality of life in symptomatic moderate–severe cases; evidence on hard cardiovascular outcomes is still limited.
When to ask your clinician: STOP-BANG ≥3 or dozing while driving: ask about testing.
Preparation: Avoid naps, caffeine and alcohol on the day.

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Oral screening & periodontal exam

— · Oral cancer screening & periodontal exam · Other specialist tests

What it measures: Visual and tactile mucosal examination; periodontal pocket depth (probe) and bleeding index.
Why it is ordered: Oral cancer screening for betel, tobacco and alcohol users; periodontal assessment in diabetes and kidney disease (linked to systemic inflammation).
Unit · Example reference range: mm；分級
Pocket ≤3 mm healthy; 4–5 mm mild–moderate; ≥6 mm severe periodontitis
What can skew the result: Smoking masks gum bleeding and underestimates periodontitis; ciclosporin and calcium-channel blockers can cause gum overgrowth.
How to read an abnormal result: White/red patches lasting >2 weeks need biopsy; periodontal treatment modestly improves HbA1c.
When to ask your clinician: Before dental care, dialysis/transplant patients should mention medicines, fistula side and dialysis days.
Preparation: Bring a medication list; with a heart valve or transplant ask about prophylactic antibiotics before scaling.

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