Hyponatremia home testing - My father has terminal cancer and hyponatremia, is there a home tester we can buy?

We wish to bring him home from hospital so that he may be comfortable at home with paliative care, currently we are being told that he needs to go to an end of life hospice where they can monitor and treat the low sodium. We wish to have him at home, only visiting hospitals when treatment is needed for the hyponatremia rather than have him permenantly reside in an end of life hospice. Is there anything commerically available that we can get to test his blood sodium levels? I know that treatment is dangerous due to complications of administering sodium sailine too quickly, etc so do not wish to treat this at home per s�. Surely there are something like the blood glucose tester strips that a diabetic requires?