diff --git a/src/components/timeline/__tests__/timeline-labs.browser.test.tsx b/src/components/timeline/__tests__/timeline-labs.browser.test.tsx
index 1860f3470..25e2cf1b4 100644
--- a/src/components/timeline/__tests__/timeline-labs.browser.test.tsx
+++ b/src/components/timeline/__tests__/timeline-labs.browser.test.tsx
@@ -232,6 +232,54 @@ describe("lab lines on the timeline page", () => {
     await expect.poll(() => lastTimelineValues(net)).toEqual(["WEIGHT"]);
   });
 
+  it("keeps a chosen marker that was hidden since, until it is unticked", async () => {
+    await page.viewport(1280, 900);
+    window.localStorage.setItem(
+      VALUES_KEY,
+      JSON.stringify(["lab:bm-ferritin"]),
+    );
+    setSearch("?zoom=all");
+    // Hidden: the server no longer offers it, and still draws the chosen line.
+    const net = stubFetch()
+      .on("GET", "/api/timeline", (request) => {
+        const body = timeline(valuesOf(request.path));
+        return {
+          data: {
+            ...body,
+            availableLabs: body.availableLabs.filter(
+              (m) => m.key !== "lab:bm-ferritin",
+            ),
+          },
+        };
+      })
+      .on("GET", "/api/timeline/readiness", {
+        data: { verdict: "carries", since: "2024-01-01", lanes: [] },
+      })
+      .on("GET", "/api/life-events", { data: { events: [] } });
+    const { screen } = await renderWithApp(<TimelineView />, {
+      user: {
+        timezone: "Europe/Berlin",
+        modules: { timeline: true, labs: true },
+      },
+    });
+    await screen.getByRole("button", { name: /Values \(1\)/ }).click();
+    const ferritin = screen.getByRole("menuitemcheckbox", { name: "Ferritin" });
+    await expect.element(ferritin).toHaveAttribute("aria-checked", "true");
+
+    await ferritin.click();
+    await expect.poll(() => lastTimelineValues(net)).toEqual([]);
+    // Unticked, it is offered no more.
+    await expect
+      .poll(
+        () =>
+          document.querySelectorAll(
+            '[data-slot="timeline-values-option"][data-key="lab:bm-ferritin"]',
+          ).length,
+      )
+      .toBe(0);
+    expect(JSON.parse(window.localStorage.getItem(VALUES_KEY)!)).toEqual([]);
+  });
+
   it("neither offers nor asks for a marker with the labs module off", async () => {
     await page.viewport(1280, 900);
     const { net, screen } = await mount(["WEIGHT", "lab:bm-ferritin"], {
diff --git a/src/lib/timeline/lab-series.ts b/src/lib/timeline/lab-series.ts
index d48838a13..b13d3a17e 100644
--- a/src/lib/timeline/lab-series.ts
+++ b/src/lib/timeline/lab-series.ts
@@ -280,7 +280,11 @@ export async function loadLabSeries(args: {
 /**
  * Every marker the record has a numeric reading for, whatever the window,
  * by name. A marker with only qualitative readings ("negative") has nothing
- * to draw and is not offered.
+ * to draw and is not offered, and neither is a hidden one: hiding a marker
+ * takes it out of the labs catalogue and the entry pickers, and this picker
+ * follows. A hidden marker already chosen keeps its line (`loadLabSeries`
+ * does not filter), and the menu names it from that line, so it can still
+ * be unticked, as the entry form keeps a hidden marker already selected.
  */
 export async function loadAvailableLabMarkers(args: {
   recordId: string;
@@ -302,7 +306,7 @@ export async function loadAvailableLabMarkers(args: {
     .filter((id): id is string => id !== null);
   if (ids.length === 0) return [];
   const markers = await prisma.biomarker.findMany({
-    where: { userId: recordId, id: { in: ids } },
+    where: { userId: recordId, id: { in: ids }, hidden: false },
     select: { id: true, name: true, panel: true, unit: true },
     orderBy: [{ name: "asc" }, { id: "asc" }],
   });
diff --git a/tests/integration/timeline-lab-series.test.ts b/tests/integration/timeline-lab-series.test.ts
index 5fc0767c6..48a71e6ca 100644
--- a/tests/integration/timeline-lab-series.test.ts
+++ b/tests/integration/timeline-lab-series.test.ts
@@ -287,6 +287,30 @@ describe("lab lines on the timeline", () => {
     expect(empty.labSeries[0]).toMatchObject({ points: [], excluded: 0 });
   });
 
+  it("does not offer a hidden marker, and keeps drawing one already chosen", async () => {
+    const owner = await makeUser("owner");
+    const { marker } = await seedFerritin(owner.id);
+    await getPrismaClient().biomarker.update({
+      where: { id: marker.id },
+      data: { hidden: true },
+    });
+    await signIn(owner.id);
+
+    // Hidden from the picker, as from the labs catalogue and entry pickers.
+    const offered = await data(await getTimeline(`zoom=all&values=WEIGHT`));
+    expect(offered.availableLabs).toEqual([]);
+    // A line chosen before it was hidden still draws, and still names
+    // itself, so the menu can untick it.
+    const chosen = await data(
+      await getTimeline(`zoom=all&values=lab:${marker.id}`),
+    );
+    expect(chosen.availableLabs).toEqual([]);
+    expect(chosen.labSeries.map((line) => [line.key, line.name])).toEqual([
+      [`lab:${marker.id}`, "Ferritin"],
+    ]);
+    expect(chosen.labSeries[0].points).toHaveLength(3);
+  });
+
   it("finds nothing under another record's marker id, and does not refuse", async () => {
     const owner = await makeUser("owner");
     const other = await makeUser("other");