There's a blood test for that

UNTIL recently, scientists could glean only so much information from what's circulating through your veins. They could grab basics like white- and red-blood-cell counts, vitamin and electrolyte levels, and markers for kidney function. They could measure cholesterol and blood-sugar numbers.

Despite Theranos's spectacular fail, top doctors today say your blood still can unlock important details about your health. Previously, markers of disease in the bloodstream were too small and too complex to pick up on. And that was more or less that.

But step-by-step advances in technology mean blood can be analysed and studied faster, cheaper, and more effectively than ever. There's now blood testing for the detection and treatment of cancer (which could take the place of a painful biopsy) and promising tests for heart disease, depression, and even the extent of chronic pain.