diff --git a/app/routers.py b/app/routers.py
index aae9a23..be83f41 100644
--- a/app/routers.py
+++ b/app/routers.py
@@ -785,6 +785,7 @@ def get_status(unit_id: str, db: Session = Depends(get_db)):
             "unit_id": unit_id,
             "last_seen": status.last_seen.isoformat() if status.last_seen else None,
             "measurement_state": status.measurement_state,
+            "measurement_start_time": status.measurement_start_time.isoformat() if status.measurement_start_time else None,
             "lp": status.lp,
             "leq": status.leq,
             "lmax": status.lmax,
@@ -843,6 +844,7 @@ def upsert_status(unit_id: str, payload: StatusPayload, db: Session = Depends(ge
             "unit_id": unit_id,
             "last_seen": status.last_seen.isoformat(),
             "measurement_state": status.measurement_state,
+            "measurement_start_time": status.measurement_start_time.isoformat() if status.measurement_start_time else None,
             "lp": status.lp,
             "leq": status.leq,
             "lmax": status.lmax,