This section shows how diagnostic tests can be used in differential diagnosis and difficult diagnostic challenges. Material is presented in tabular format, and contents are listed in alphabetical order by disease topic.
Abbreviations used throughout this section include the following:
N = Normal
Abn = Abnormal
Pos = Positive
Neg = Negative
↑ = Increased or high
↓ = Decreased or low
Occ = Occasional
ACID–BASE DISTURBANCE: LABORATORY CHARACTERISTICS OF PRIMARY OR SINGLE ACID–BASE DISTURBANCE
TABLE 8–1.ACID–BASE DISTURBANCE: LABORATORY CHARACTERISTICS OF PRIMARY OR SINGLE ACID–BASE DISTURBANCE. |Favorite Table|Download (.pdf) TABLE 8–1. ACID–BASE DISTURBANCE: LABORATORY CHARACTERISTICS OF PRIMARY OR SINGLE ACID–BASE DISTURBANCE.
|Disturbance ||Acute Primary Change ||Partial Compensatory Response ||Arterial pH ||Serum [K+] (meq/L) ||Anion Gap1 (Unmeasured Anions) (meq/L) ||Clinical Features |
|Normal ||None ||None ||7.35–7.45 ||3.5–5.0 ||6–12 ||None |
|Respiratory acidosis ||PCO2 ↑ (CO2 retention) ||↑ HCO3– ||↓ ||↑ ||N ||Dyspnea, polypnea, respiratory outflow obstruction,↑ anterior-posterior chest diameter, rales, wheezes. In severe cases, stupor, disorientation, coma. |
|Respiratory alkalosis ||PCO2 ↓ (CO2 depletion) ||↓ HCO3– ||↑ ||↓ ||N or ↓ ||Anxiety, occasional complaint of breathlessness, frequent sighing, lungs usually clear to examination, positive Chvostek and Trousseau signs. |
|Metabolic acidosis ||HCO3– depletion ||↓ PCO2 ||↓ ||↑ or ↓ ||N or ↑ ||Weakness, air hunger, Kussmaul respiration, dry skin and mucous membranes, poor skin turgor. In severe cases, coma, hypotension, death. |
|Metabolic alkalosis ||HCO3– retention ||↑ PCO2 ||↑ ||↓ ||N ||Weakness, positive Chvostek and Trousseau signs, hyporeflexia. |
ANEMIA: DIAGNOSIS OF COMMON ANEMIAS BASED ON RED CELL INDICES
TABLE 8–2.ANEMIA: DIAGNOSIS OF COMMON ANEMIAS BASED ON RED CELL INDICES. |Favorite Table|Download (.pdf) TABLE 8–2. ANEMIA: DIAGNOSIS OF COMMON ANEMIAS BASED ON RED CELL INDICES.
|Type of Anemia ||MCV (fL) ||MCHC (g/dL) ||Common Causes ||Common Laboratory Abnormalities ||Clinical Findings |
|Microcytic, hypochromic ||<80 ||<32 ||Iron deficiency ||Hypochromic red cells, elliptocytes, low reticulocyte count, low serum ferritin, low serum iron and absent bone marrow iron, high TIBC, high serum/plasma soluble transferrin receptor (sTfR). ||Mucositis, brittle nails, bleeding (eg, positive fecal occult blood, menorrhagia), esophageal webs, pica. |
|Variable, but usually <32 ||Thalassemias ||Abnormal red cell morphology, normal to high RBC count, elevated reticulocyte count, normal serum iron parameters, abnormal hemoglobin electrophoresis, high hemoglobin A...|