diff --git a/server/src/lib/analytes.ts b/server/src/lib/analytes.ts
index 75f8b68..7aa262f 100644
--- a/server/src/lib/analytes.ts
+++ b/server/src/lib/analytes.ts
@@ -85,7 +85,7 @@ export const ANALYTES: Analyte[] = [
     key: "dhea_s",
     display: "DHEA-S",
     canonicalUnit: "µmol/L",
-    molarMass: 384.5,
+    molarMass: 368.49,
     panel: "hormones",
     aliases: ["dhea-s", "dhea s", "dheas", "dehydroepiandrosterone sulfate"],
   },
@@ -347,7 +347,12 @@ export const ANALYTES: Analyte[] = [
     canonicalUnit: "mmol/L",
     molarMass: 60.06,
     panel: "kidney",
-    aliases: ["urea", "bun", "blood urea nitrogen"],
+    // Deliberately no "bun"/"blood urea nitrogen" aliases: BUN mg/dL -> urea
+    // mmol/L needs the nitrogen divisor (2N = 28.01 g/mol), not urea's own
+    // molar mass (60.06). Mapping BUN here would silently under-convert by
+    // ~2.14x. BUN rows stay unmapped (raw value preserved) until a proper
+    // BUN analyte with its own divisor is added.
+    aliases: ["urea"],
   },
 
   // --- cbc ---
diff --git a/server/test/normalize.test.ts b/server/test/normalize.test.ts
index 34589b4..ebf338c 100644
--- a/server/test/normalize.test.ts
+++ b/server/test/normalize.test.ts
@@ -52,4 +52,13 @@ describe("normalizeMarker", () => {
     expect(n.valueNum).toBeCloseTo(0.3);
     expect(n.value).toBe("<0.3");
   });
+  test("BUN is not mapped onto urea (needs N-divisor, not molar mass)", () => {
+    expect(resolveAnalyte("BUN")).toBeNull();
+    expect(resolveAnalyte("blood urea nitrogen")).toBeNull();
+    expect(resolveAnalyte("urea")?.key).toBe("urea");
+  });
+  test("DHEA-S µg/dL converts with corrected molar mass", () => {
+    const n = normalizeMarker({ name: "DHEA-S", value: "250", unit: "ug/dL" });
+    expect(n.valueCanonical).toBeCloseTo(6.78, 1); // 250 * 0.02713
+  });
 });