Apple's Passbook app

This week 9to5Mac dropped its latest report on the rumored all-in-one health tracking app that Apple is reportedly working on in tandem with a wristworn, health sensing iWatch device. The report includes a number of "complete recreations of screenshots" of Healthbook's user interface that the publication received from anonymous sources.

As has been reported before, the images depict an app very similar to Apple's Passbook app, which helps users store loyalty cards and coupons. Like Passbook, Healthbook would be designed with an interface that resembles a stack of cards — each card representing a different group of health or fitness data points.

9to5Mac claims the app will include cards for tracking: bloodwork, heart rate, hydration, blood pressure, activity, nutrition, sleep, respiration rate, oxygen saturation, weight, blood sugar, and emergency information.

In late January when 9to5Mac first reported that Apple was working on an app called Healthbook, it reported: "Based on the health information that iOS 8 is capable of reading, Apple’s wearable device will seemingly have sensors at least capable of measuring blood pressure, hydration, heart rate, and steps. iOS 8 combined with the iWatch is said to be able to monitor several other pieces of health and fitness data, but additional specifics are not as clear as of now."

MobiHealthNews has been skeptical about claims that Apple's iWatch would include hydration sensing capabilities.

Hydration sensors are in the works at companies like MC10, but finding a way to integrate a similar sensor into a multisensor, wristworn device would be quite a feat for the iPhone maker. Sources with inside knowledge of iWatch development have told MobiHealthNews that the device will not include hydration sensing.

Unless Apple is launching Healthbook with partners (like MC10) that are working on complementary sensor devices, including a manual hydration tracking feature (how many glasses of water have you had today?) would be a less than impressive Healthbook feature. That said, such manual trackers for water consumption do exist in the AppStore already and Apple, of course, has the best data on which apps have gained traction in the market.

Many of the features Healthbook will reportedly help users track will require Healthbook users to pull in data from third party apps and devices. Unless Apple goes the unlikely route of creating an FDA regulated medical device, it will need to pull in blood glucose data from other apps or devices, perhaps from FDA-regulated apps like those made by Sanofi or Glooko. MobiHealthNews has also speculated previously as to whether Apple has hired so many non-invasive glucose sensor experts to attempt an automatic caloric-intake sensor like Healbe purports to be developing.

Weight is another biometric we've yet to see a wristworn device measure. The recreated screenshots over at 9to5Mac also show body fat percentage data in the "weight" tab of the app, which indicates the scale used to measure that body fat percentage likely has FDA clearance.

Depending on the claims Apple makes about what a user can do with the health data collected in its app, it could use a similar method to Azumio's popular Instant Heart Rate app to pull in heart rate data directly using the smartphone's camera.

While MobiHealthNews speculated earlier this year that an all-in-one health tracking app like the rumored Healthbook would likely include tracking for women's health issues -- like an ovulation calendar -- 9to5Mac's anonymous sources say that Apple will ignore women's health tracking in its first iteration. That would be a puzzling move for the typically market-savvy Apple.